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Publisher: John Wiley and Sons   (Total: 1577 journals)

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Showing 1 - 200 of 1577 Journals sorted alphabetically
Abacus     Hybrid Journal   (Followers: 12, SJR: 0.48, h-index: 22)
About Campus     Hybrid Journal   (Followers: 5)
Academic Emergency Medicine     Hybrid Journal   (Followers: 64, SJR: 1.385, h-index: 91)
Accounting & Finance     Hybrid Journal   (Followers: 46, SJR: 0.547, h-index: 30)
ACEP NOW     Free   (Followers: 1)
Acta Anaesthesiologica Scandinavica     Hybrid Journal   (Followers: 49, SJR: 1.02, h-index: 88)
Acta Archaeologica     Hybrid Journal   (Followers: 149, SJR: 0.101, h-index: 9)
Acta Geologica Sinica (English Edition)     Hybrid Journal   (Followers: 3, SJR: 0.552, h-index: 41)
Acta Neurologica Scandinavica     Hybrid Journal   (Followers: 5, SJR: 1.203, h-index: 74)
Acta Obstetricia et Gynecologica Scandinavica     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 81)
Acta Ophthalmologica     Hybrid Journal   (Followers: 5, SJR: 0.112, h-index: 1)
Acta Paediatrica     Hybrid Journal   (Followers: 56, SJR: 0.794, h-index: 88)
Acta Physiologica     Hybrid Journal   (Followers: 6, SJR: 1.69, h-index: 88)
Acta Polymerica     Hybrid Journal   (Followers: 9)
Acta Psychiatrica Scandinavica     Hybrid Journal   (Followers: 35, SJR: 2.518, h-index: 113)
Acta Zoologica     Hybrid Journal   (Followers: 6, SJR: 0.459, h-index: 29)
Acute Medicine & Surgery     Hybrid Journal   (Followers: 3)
Addiction     Hybrid Journal   (Followers: 35, SJR: 2.086, h-index: 143)
Addiction Biology     Hybrid Journal   (Followers: 13, SJR: 2.091, h-index: 57)
Adultspan J.     Hybrid Journal   (SJR: 0.127, h-index: 4)
Advanced Energy Materials     Hybrid Journal   (Followers: 26, SJR: 6.411, h-index: 86)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26, SJR: 0.81, h-index: 81)
Advanced Functional Materials     Hybrid Journal   (Followers: 50, SJR: 5.21, h-index: 203)
Advanced Healthcare Materials     Hybrid Journal   (Followers: 13, SJR: 0.232, h-index: 7)
Advanced Materials     Hybrid Journal   (Followers: 257, SJR: 9.021, h-index: 345)
Advanced Materials Interfaces     Hybrid Journal   (Followers: 6, SJR: 1.177, h-index: 10)
Advanced Optical Materials     Hybrid Journal   (Followers: 5, SJR: 2.488, h-index: 21)
Advanced Science     Open Access   (Followers: 5)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17, SJR: 2.729, h-index: 121)
Advances in Polymer Technology     Hybrid Journal   (Followers: 13, SJR: 0.344, h-index: 31)
Africa Confidential     Hybrid Journal   (Followers: 19)
Africa Research Bulletin: Economic, Financial and Technical Series     Hybrid Journal   (Followers: 12)
Africa Research Bulletin: Political, Social and Cultural Series     Hybrid Journal   (Followers: 9)
African Development Review     Hybrid Journal   (Followers: 35, SJR: 0.275, h-index: 17)
African J. of Ecology     Hybrid Journal   (Followers: 15, SJR: 0.477, h-index: 39)
Aggressive Behavior     Hybrid Journal   (Followers: 15, SJR: 1.391, h-index: 66)
Aging Cell     Open Access   (Followers: 10, SJR: 4.374, h-index: 95)
Agribusiness : an Intl. J.     Hybrid Journal   (Followers: 6, SJR: 0.627, h-index: 14)
Agricultural and Forest Entomology     Hybrid Journal   (Followers: 14, SJR: 0.925, h-index: 43)
Agricultural Economics     Hybrid Journal   (Followers: 45, SJR: 1.099, h-index: 51)
AIChE J.     Hybrid Journal   (Followers: 30, SJR: 1.122, h-index: 120)
Alcoholism and Drug Abuse Weekly     Hybrid Journal   (Followers: 7)
Alcoholism Clinical and Experimental Research     Hybrid Journal   (Followers: 7, SJR: 1.416, h-index: 125)
Alimentary Pharmacology & Therapeutics     Hybrid Journal   (Followers: 34, SJR: 2.833, h-index: 138)
Alimentary Pharmacology & Therapeutics Symposium Series     Hybrid Journal   (Followers: 3)
Allergy     Hybrid Journal   (Followers: 50, SJR: 3.048, h-index: 129)
Alternatives to the High Cost of Litigation     Hybrid Journal   (Followers: 3)
American Anthropologist     Hybrid Journal   (Followers: 137, SJR: 0.951, h-index: 61)
American Business Law J.     Hybrid Journal   (Followers: 24, SJR: 0.205, h-index: 17)
American Ethnologist     Hybrid Journal   (Followers: 89, SJR: 2.325, h-index: 51)
American J. of Economics and Sociology     Hybrid Journal   (Followers: 27, SJR: 0.211, h-index: 26)
American J. of Hematology     Hybrid Journal   (Followers: 33, SJR: 1.761, h-index: 77)
American J. of Human Biology     Hybrid Journal   (Followers: 12, SJR: 1.018, h-index: 58)
American J. of Industrial Medicine     Hybrid Journal   (Followers: 16, SJR: 0.993, h-index: 85)
American J. of Medical Genetics Part A     Hybrid Journal   (Followers: 16, SJR: 1.115, h-index: 61)
American J. of Medical Genetics Part B: Neuropsychiatric Genetics     Hybrid Journal   (Followers: 4, SJR: 1.771, h-index: 107)
American J. of Medical Genetics Part C: Seminars in Medical Genetics     Partially Free   (Followers: 6, SJR: 2.315, h-index: 79)
American J. of Physical Anthropology     Hybrid Journal   (Followers: 37, SJR: 1.41, h-index: 88)
American J. of Political Science     Hybrid Journal   (Followers: 264, SJR: 5.101, h-index: 114)
American J. of Primatology     Hybrid Journal   (Followers: 15, SJR: 1.197, h-index: 63)
American J. of Reproductive Immunology     Hybrid Journal   (Followers: 3, SJR: 1.347, h-index: 75)
American J. of Transplantation     Hybrid Journal   (Followers: 17, SJR: 2.792, h-index: 140)
American J. on Addictions     Hybrid Journal   (Followers: 9, SJR: 0.843, h-index: 57)
Anaesthesia     Hybrid Journal   (Followers: 126, SJR: 1.404, h-index: 88)
Analyses of Social Issues and Public Policy     Hybrid Journal   (Followers: 10, SJR: 0.397, h-index: 18)
Analytic Philosophy     Hybrid Journal   (Followers: 16)
Anatomia, Histologia, Embryologia: J. of Veterinary Medicine Series C     Hybrid Journal   (Followers: 3, SJR: 0.295, h-index: 27)
Anatomical Sciences Education     Hybrid Journal   (Followers: 1, SJR: 0.633, h-index: 24)
Andrologia     Hybrid Journal   (Followers: 2, SJR: 0.528, h-index: 45)
Andrology     Hybrid Journal   (Followers: 2, SJR: 0.979, h-index: 14)
Angewandte Chemie     Hybrid Journal   (Followers: 224)
Angewandte Chemie Intl. Edition     Hybrid Journal   (Followers: 213, SJR: 6.229, h-index: 397)
Animal Conservation     Hybrid Journal   (Followers: 37, SJR: 1.576, h-index: 62)
Animal Genetics     Hybrid Journal   (Followers: 9, SJR: 0.957, h-index: 67)
Animal Science J.     Hybrid Journal   (Followers: 6, SJR: 0.569, h-index: 24)
Annalen der Physik     Hybrid Journal   (Followers: 5, SJR: 1.46, h-index: 40)
Annals of Anthropological Practice     Partially Free   (Followers: 2, SJR: 0.187, h-index: 5)
Annals of Applied Biology     Hybrid Journal   (Followers: 7, SJR: 0.816, h-index: 56)
Annals of Clinical and Translational Neurology     Open Access   (Followers: 1)
Annals of Human Genetics     Hybrid Journal   (Followers: 9, SJR: 1.191, h-index: 67)
Annals of Neurology     Hybrid Journal   (Followers: 48, SJR: 5.584, h-index: 241)
Annals of Noninvasive Electrocardiology     Hybrid Journal   (Followers: 2, SJR: 0.531, h-index: 38)
Annals of Public and Cooperative Economics     Hybrid Journal   (Followers: 9, SJR: 0.336, h-index: 23)
Annals of the New York Academy of Sciences     Hybrid Journal   (Followers: 5, SJR: 2.389, h-index: 189)
Annual Bulletin of Historical Literature     Hybrid Journal   (Followers: 13)
Annual Review of Information Science and Technology     Hybrid Journal   (Followers: 14)
Anthropology & Education Quarterly     Hybrid Journal   (Followers: 24, SJR: 0.72, h-index: 31)
Anthropology & Humanism     Hybrid Journal   (Followers: 17, SJR: 0.137, h-index: 3)
Anthropology News     Hybrid Journal   (Followers: 15)
Anthropology of Consciousness     Hybrid Journal   (Followers: 11, SJR: 0.172, h-index: 5)
Anthropology of Work Review     Hybrid Journal   (Followers: 11, SJR: 0.256, h-index: 5)
Anthropology Today     Hybrid Journal   (Followers: 91, SJR: 0.545, h-index: 15)
Antipode     Hybrid Journal   (Followers: 47, SJR: 2.212, h-index: 69)
Anz J. of Surgery     Hybrid Journal   (Followers: 7, SJR: 0.432, h-index: 59)
Anzeiger für Schädlingskunde     Hybrid Journal   (Followers: 1)
Apmis     Hybrid Journal   (Followers: 1, SJR: 0.855, h-index: 73)
Applied Cognitive Psychology     Hybrid Journal   (Followers: 68, SJR: 0.754, h-index: 69)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 7, SJR: 0.632, h-index: 58)
Applied Psychology     Hybrid Journal   (Followers: 151, SJR: 1.023, h-index: 64)
Applied Psychology: Health and Well-Being     Hybrid Journal   (Followers: 48, SJR: 0.868, h-index: 13)
Applied Stochastic Models in Business and Industry     Hybrid Journal   (Followers: 5, SJR: 0.613, h-index: 24)
Aquaculture Nutrition     Hybrid Journal   (Followers: 14, SJR: 1.025, h-index: 55)
Aquaculture Research     Hybrid Journal   (Followers: 31, SJR: 0.807, h-index: 60)
Aquatic Conservation Marine and Freshwater Ecosystems     Hybrid Journal   (Followers: 36, SJR: 1.047, h-index: 57)
Arabian Archaeology and Epigraphy     Hybrid Journal   (Followers: 11, SJR: 0.453, h-index: 11)
Archaeological Prospection     Hybrid Journal   (Followers: 12, SJR: 0.922, h-index: 21)
Archaeology in Oceania     Hybrid Journal   (Followers: 13, SJR: 0.745, h-index: 18)
Archaeometry     Hybrid Journal   (Followers: 27, SJR: 0.809, h-index: 48)
Archeological Papers of The American Anthropological Association     Hybrid Journal   (Followers: 15, SJR: 0.156, h-index: 2)
Architectural Design     Hybrid Journal   (Followers: 25, SJR: 0.261, h-index: 9)
Archiv der Pharmazie     Hybrid Journal   (Followers: 4, SJR: 0.628, h-index: 43)
Archives of Drug Information     Hybrid Journal   (Followers: 4)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (SJR: 0.768, h-index: 54)
Area     Hybrid Journal   (Followers: 12, SJR: 0.938, h-index: 57)
Art History     Hybrid Journal   (Followers: 237, SJR: 0.153, h-index: 13)
Arthritis & Rheumatology     Hybrid Journal   (Followers: 51, SJR: 1.984, h-index: 20)
Arthritis Care & Research     Hybrid Journal   (Followers: 27, SJR: 2.256, h-index: 114)
Artificial Organs     Hybrid Journal   (Followers: 1, SJR: 0.872, h-index: 60)
ASHE Higher Education Reports     Hybrid Journal   (Followers: 14)
Asia & the Pacific Policy Studies     Open Access   (Followers: 15)
Asia Pacific J. of Human Resources     Hybrid Journal   (Followers: 312, SJR: 0.494, h-index: 19)
Asia Pacific Viewpoint     Hybrid Journal   (Followers: 1, SJR: 0.616, h-index: 26)
Asia-Pacific J. of Chemical Engineering     Hybrid Journal   (Followers: 8, SJR: 0.345, h-index: 20)
Asia-pacific J. of Clinical Oncology     Hybrid Journal   (Followers: 6, SJR: 0.554, h-index: 14)
Asia-Pacific J. of Financial Studies     Hybrid Journal   (SJR: 0.241, h-index: 7)
Asia-Pacific Psychiatry     Hybrid Journal   (Followers: 4, SJR: 0.377, h-index: 7)
Asian Economic J.     Hybrid Journal   (Followers: 8, SJR: 0.234, h-index: 21)
Asian Economic Policy Review     Hybrid Journal   (Followers: 4, SJR: 0.196, h-index: 12)
Asian J. of Control     Hybrid Journal   (SJR: 0.862, h-index: 34)
Asian J. of Endoscopic Surgery     Hybrid Journal   (SJR: 0.394, h-index: 7)
Asian J. of Organic Chemistry     Hybrid Journal   (Followers: 4, SJR: 1.443, h-index: 19)
Asian J. of Social Psychology     Hybrid Journal   (Followers: 5, SJR: 0.665, h-index: 37)
Asian Politics and Policy     Hybrid Journal   (Followers: 12, SJR: 0.207, h-index: 7)
Asian Social Work and Policy Review     Hybrid Journal   (Followers: 5, SJR: 0.318, h-index: 5)
Asian-pacific Economic Literature     Hybrid Journal   (Followers: 5, SJR: 0.168, h-index: 15)
Assessment Update     Hybrid Journal   (Followers: 4)
Astronomische Nachrichten     Hybrid Journal   (Followers: 2, SJR: 0.701, h-index: 40)
Atmospheric Science Letters     Open Access   (Followers: 29, SJR: 1.332, h-index: 27)
Austral Ecology     Hybrid Journal   (Followers: 13, SJR: 1.095, h-index: 66)
Austral Entomology     Hybrid Journal   (Followers: 9, SJR: 0.524, h-index: 28)
Australasian J. of Dermatology     Hybrid Journal   (Followers: 8, SJR: 0.714, h-index: 40)
Australasian J. On Ageing     Hybrid Journal   (Followers: 7, SJR: 0.39, h-index: 22)
Australian & New Zealand J. of Statistics     Hybrid Journal   (Followers: 13, SJR: 0.275, h-index: 28)
Australian Accounting Review     Hybrid Journal   (Followers: 4, SJR: 0.709, h-index: 14)
Australian and New Zealand J. of Family Therapy (ANZJFT)     Hybrid Journal   (Followers: 3, SJR: 0.382, h-index: 12)
Australian and New Zealand J. of Obstetrics and Gynaecology     Hybrid Journal   (Followers: 44, SJR: 0.814, h-index: 49)
Australian and New Zealand J. of Public Health     Hybrid Journal   (Followers: 11, SJR: 0.82, h-index: 62)
Australian Dental J.     Hybrid Journal   (Followers: 7, SJR: 0.482, h-index: 46)
Australian Economic History Review     Hybrid Journal   (Followers: 4, SJR: 0.171, h-index: 12)
Australian Economic Papers     Hybrid Journal   (Followers: 27, SJR: 0.23, h-index: 9)
Australian Economic Review     Hybrid Journal   (Followers: 6, SJR: 0.357, h-index: 21)
Australian Endodontic J.     Hybrid Journal   (Followers: 3, SJR: 0.513, h-index: 24)
Australian J. of Agricultural and Resource Economics     Hybrid Journal   (Followers: 3, SJR: 0.765, h-index: 36)
Australian J. of Grape and Wine Research     Hybrid Journal   (Followers: 5, SJR: 0.879, h-index: 56)
Australian J. of Politics & History     Hybrid Journal   (Followers: 14, SJR: 0.203, h-index: 14)
Australian J. of Psychology     Hybrid Journal   (Followers: 18, SJR: 0.384, h-index: 30)
Australian J. of Public Administration     Hybrid Journal   (Followers: 405, SJR: 0.418, h-index: 29)
Australian J. of Rural Health     Hybrid Journal   (Followers: 4, SJR: 0.43, h-index: 34)
Australian Occupational Therapy J.     Hybrid Journal   (Followers: 69, SJR: 0.59, h-index: 29)
Australian Psychologist     Hybrid Journal   (Followers: 11, SJR: 0.331, h-index: 31)
Australian Veterinary J.     Hybrid Journal   (Followers: 19, SJR: 0.459, h-index: 45)
Autism Research     Hybrid Journal   (Followers: 32, SJR: 2.126, h-index: 39)
Autonomic & Autacoid Pharmacology     Hybrid Journal   (SJR: 0.371, h-index: 29)
Banks in Insurance Report     Hybrid Journal   (Followers: 1)
Basic & Clinical Pharmacology & Toxicology     Hybrid Journal   (Followers: 10, SJR: 0.539, h-index: 70)
Basic and Applied Pathology     Open Access   (Followers: 2, SJR: 0.113, h-index: 4)
Basin Research     Hybrid Journal   (Followers: 5, SJR: 1.54, h-index: 60)
Bauphysik     Hybrid Journal   (Followers: 2, SJR: 0.194, h-index: 5)
Bauregelliste A, Bauregelliste B Und Liste C     Hybrid Journal  
Bautechnik     Hybrid Journal   (Followers: 1, SJR: 0.321, h-index: 11)
Behavioral Interventions     Hybrid Journal   (Followers: 9, SJR: 0.297, h-index: 23)
Behavioral Sciences & the Law     Hybrid Journal   (Followers: 24, SJR: 0.736, h-index: 57)
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 9, SJR: 0.11, h-index: 5)
Beton- und Stahlbetonbau     Hybrid Journal   (Followers: 2, SJR: 0.493, h-index: 14)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 6, SJR: 0.311, h-index: 26)
Bioelectromagnetics     Hybrid Journal   (Followers: 1, SJR: 0.568, h-index: 64)
Bioengineering & Translational Medicine     Open Access  
BioEssays     Hybrid Journal   (Followers: 10, SJR: 3.104, h-index: 155)
Bioethics     Hybrid Journal   (Followers: 14, SJR: 0.686, h-index: 39)
Biofuels, Bioproducts and Biorefining     Hybrid Journal   (Followers: 1, SJR: 1.725, h-index: 56)
Biological J. of the Linnean Society     Hybrid Journal   (Followers: 16, SJR: 1.172, h-index: 90)
Biological Reviews     Hybrid Journal   (Followers: 3, SJR: 6.469, h-index: 114)
Biologie in Unserer Zeit (Biuz)     Hybrid Journal   (Followers: 42, SJR: 0.12, h-index: 1)
Biology of the Cell     Full-text available via subscription   (Followers: 9, SJR: 1.812, h-index: 69)
Biomedical Chromatography     Hybrid Journal   (Followers: 6, SJR: 0.572, h-index: 49)
Biometrical J.     Hybrid Journal   (Followers: 5, SJR: 0.784, h-index: 44)
Biometrics     Hybrid Journal   (Followers: 36, SJR: 1.906, h-index: 96)
Biopharmaceutics and Drug Disposition     Hybrid Journal   (Followers: 10, SJR: 0.715, h-index: 44)
Biopolymers     Hybrid Journal   (Followers: 18, SJR: 1.199, h-index: 104)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 45, SJR: 0.415, h-index: 55)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 193, SJR: 1.633, h-index: 146)
Biotechnology J.     Hybrid Journal   (Followers: 14, SJR: 1.185, h-index: 51)
Biotechnology Progress     Hybrid Journal   (Followers: 39, SJR: 0.736, h-index: 101)
Biotropica     Hybrid Journal   (Followers: 19, SJR: 1.374, h-index: 71)
Bipolar Disorders     Hybrid Journal   (Followers: 9, SJR: 2.592, h-index: 100)
Birth     Hybrid Journal   (Followers: 37, SJR: 0.763, h-index: 64)
Birth Defects Research Part A : Clinical and Molecular Teratology     Hybrid Journal   (Followers: 2, SJR: 0.727, h-index: 77)
Birth Defects Research Part B: Developmental and Reproductive Toxicology     Hybrid Journal   (Followers: 5, SJR: 0.468, h-index: 47)
Birth Defects Research Part C : Embryo Today : Reviews     Hybrid Journal   (SJR: 1.513, h-index: 55)
BJOG : An Intl. J. of Obstetrics and Gynaecology     Partially Free   (Followers: 226, SJR: 2.083, h-index: 125)

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Journal Cover Advanced Materials
  [SJR: 9.021]   [H-I: 345]   [257 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0935-9648 - ISSN (Online) 1521-4095
   Published by John Wiley and Sons Homepage  [1577 journals]
  • Robust Catalysis on 2D Materials Encapsulating Metals: Concept,
           Application, and Perspective
    • Authors: Jiao Deng; Dehui Deng, Xinhe Bao
      Abstract: Great endeavors are undertaken to search for low-cost, rich-reserve, and highly efficient alternatives to replace precious-metal catalysts, in order to cut costs and improve the efficiency of catalysts in industry. However, one major problem in metal catalysts, especially nonprecious-metal catalysts, is their poor stability in real catalytic processes. Recently, a novel and promising strategy to construct 2D materials encapsulating nonprecious-metal catalysts has exhibited inimitable advantages toward catalysis, especially under harsh conditions (e.g., strong acidity or alkalinity, high temperature, and high overpotential). The concept, which originates from unique electron penetration through the 2D crystal layer from the encapsulated metals to promote a catalytic reaction on the outermost surface of the 2D crystal, has been widely applied in a variety of reactions under harsh conditions. It has been vividly described as “chainmail for catalyst.” Herein, recent progress concerning this chainmail catalyst is reviewed, particularly focusing on the structural design and control with the associated electronic properties of such heterostructure catalysts, and also on their extensive applications in fuel cells, water splitting, CO2 conversion, solar cells, metal–air batteries, and heterogeneous catalysis. In addition, the current challenges that are faced in fundamental research and industrial application, and future opportunities for these fantastic catalytic materials are discussed.A new catalytic concept is systematically reviewed based on robust catalysts via utilizing electron penetration from encapsulated metal nanoparticles to the surface of 2D materials, described vividly as “chainmail for catalyst.” Furthermore, structural and electronic optimization, including the flexible combination of metal nanoparticles and 2D materials, enrich such a class of catalysts and boost them into more applications.
      PubDate: 2017-09-22T07:17:30.999226-05:
      DOI: 10.1002/adma.201606967
       
  • Nonaqueous Hybrid Lithium-Ion and Sodium-Ion Capacitors
    • Authors: Huanwen Wang; Changrong Zhu, Dongliang Chao, Qingyu Yan, Hong Jin Fan
      Abstract: Hybrid metal-ion capacitors (MICs) (M stands for Li or Na) are designed to deliver high energy density, rapid energy delivery, and long lifespan. The devices are composed of a battery anode and a supercapacitor cathode, and thus become a tradeoff between batteries and supercapacitors. In the past two decades, tremendous efforts have been put into the search for suitable electrode materials to overcome the kinetic imbalance between the battery-type anode and the capacitor-type cathode. Recently, some transition-metal compounds have been found to show pseudocapacitive characteristics in a nonaqueous electrolyte, which makes them interesting high-rate candidates for hybrid MIC anodes. Here, the material design strategies in Li-ion and Na-ion capacitors are summarized, with a focus on pseudocapacitive oxide anodes (Nb2O5, MoO3, etc.), which provide a new opportunity to obtain a higher power density of the hybrid devices. The application of Mxene as an anode material of MICs is also discussed. A perspective to the future research of MICs toward practical applications is proposed to close.Hybrid metal-ion capacitors are found to deliver high energy density and rapid energy delivery. The material design strategies particularly in pseudocapacitive oxide anodes in Li-ion and Na-ion capacitors (LICs and NICs) are systematically discussed. A perspective on the challenges and opportunities of LIC and NIC devices is also presented.
      PubDate: 2017-09-22T07:16:26.528726-05:
      DOI: 10.1002/adma.201702093
       
  • Unveiling Active Sites for the Hydrogen Evolution Reaction on Monolayer
           MoS2
    • Authors: Jing Zhang; Jingjie Wu, Hua Guo, Weibing Chen, Jiangtan Yuan, Ulises Martinez, Gautam Gupta, Aditya Mohite, Pulickel M. Ajayan, Jun Lou
      Abstract: Here, the hydrogen evolution reaction (HER) activities at the edge and basal-plane sites of monolayer molybdenum disulfide (MoS2) synthesized by chemical vapor deposition (CVD) are studied using a local probe method enabled by selected-area lithography. Reaction windows are opened by e-beam lithography at sites of interest on poly(methyl methacrylate) (PMMA)-covered monolayer MoS2 triangles. The HER properties of MoS2 edge sites are obtained by subtraction of the activity of the basal-plane sites from results containing both basal-plane and edge sites. The catalytic performances in terms of turnover frequencies (TOFs) are calculated based on the estimated number of active sites on the selected areas. The TOFs follow a descending order of 3.8 ± 1.6, 1.6 ± 1.2, 0.008 ± 0.002, and 1.9 ± 0.8 × 10−4 s−1, found for 1T′-, 2H-MoS2 edges, and 1T′-, 2H-MoS2 basal planes, respectively. Edge sites of both 2H- and 1T′-MoS2 are proved to have comparable activities to platinum (≈1–10 s−1). When fitted into the HER volcano plot, the MoS2 active sites follow a trend distinct from conventional metals, implying a possible difference in the reaction mechanism between transition-metal dichalcogenides (TMDs) and metal catalysts.Utilizing an on-chip electrochemical device, which is capable of measuring the hydrogen-evolution performance on the designated location of monolayer MoS2, the catalytic activities of the basal-plane and edge sites of both 2H and 1T′-MoS2 are identified. The activities of the MoS2 active sites follow a unique trend in the volcano plot.
      PubDate: 2017-09-22T07:15:36.833488-05:
      DOI: 10.1002/adma.201701955
       
  • A Superhydrophobic Smart Coating for Flexible and Wearable Sensing
           Electronics
    • Authors: Lianhui Li; Yuanyuan Bai, Lili Li, Shuqi Wang, Ting Zhang
      Abstract: Superhydrophobic surfaces have shown versatile applications in waterproofing, self-cleaning, drag reduction, selective absorption, etc. The most convenient and universally applicable approach to forming superhydrophobic surfaces is by coating; however, currently, superhydrophobic, smart coatings with flexibility and multiple functions for wearable sensing electronics are not yet reported. Here, a highly flexible multifunctional smart coating is fabricated by spray-coating multiwalled carbon nanotubes dispersed in a thermoplastic elastomer solution, followed by treatment with ethanol. The coatings not only endow various substrate materials with superhydrophobic surfaces, but can also respond to stretching, bending, and torsion—a property useful for flexible sensor applications. The coatings show superior sensitivity (gauge factor of 5.4–80), high resolution (1° of bending), a fast response time (
      PubDate: 2017-09-22T07:12:09.24013-05:0
      DOI: 10.1002/adma.201702517
       
  • Single-Molecule Spectroscopy: In Situ Two-Step Photoreduced SERS Materials
           for On-Chip Single-Molecule Spectroscopy with High Reproducibility (Adv.
           Mater. 36/2017)
    • Authors: Wenjie Yan; Longkun Yang, Jianing Chen, Yaqi Wu, Peijie Wang, Zhipeng Li
      Abstract: Highly reproducible on-chip single-molecule Raman detection is achieved by developing a two-step photoreduction approach to incorporate surface-enhanced Raman scattering (SERS) materials with microfluidics, as reported by Zhipeng Li and co-workers in article number 1702893. The detection limit for various types of molecules can be as low as 10−13 m with reproducibility of about 50%. This work may lead to substantial advances in single-molecule spectroscopy and quantitative SERS detection.
      PubDate: 2017-09-21T07:46:40.762238-05:
      DOI: 10.1002/adma.201770261
       
  • Drug Delivery: Engineering the Surface of Smart Nanocarriers Using a
           pH-/Thermal-/GSH-Responsive Polymer Zipper for Precise Tumor Targeting
           Therapy In Vivo (Adv. Mater. 36/2017)
    • Authors: Penghui Zhang; Yan Wang, Jing Lian, Qi Shen, Chen Wang, Bohan Ma, Yuchao Zhang, Tingting Xu, Jianxin Li, Yongping Shao, Feng Xu, Jun-Jie Zhu
      Abstract: In article number 1702311, Feng Xu, Jun-Jie Zhu, and co-workers tune nanocarrier surface compositions on command for precise tumor targeting by way of pH-/thermal-/glutathione-responsive polymer zippers. The nanocarriers remain stealthy during blood circulation, but their surfaces are activated by the acidic microenvironment and photothermal heating at tumor sites for enhanced cellular uptake and efficient drug release.
      PubDate: 2017-09-21T07:46:40.709645-05:
      DOI: 10.1002/adma.201770263
       
  • Graphene: Preventing Thin Film Dewetting via Graphene Capping (Adv. Mater.
           36/2017)
    • Authors: Peigen Cao; Peter Bai, Arash A. Omrani, Yihan Xiao, Kacey L. Meaker, Hsin-Zon Tsai, Aiming Yan, Han Sae Jung, Ramin Khajeh, Griffin F. Rodgers, Youngkyou Kim, Andrew S. Aikawa, Mattew A. Kolaczkowski, Yi Liu, Alex Zettl, Ke Xu, Michael F. Crommie, Ting Xu
      Abstract: A single layer of a 2D material with a high Young's modulus such as graphene may be transferred onto a thin-film surface as a “cap” to prevent dewetting, which has classically plagued thermal and chemical processing steps. The difference between capped and uncapped surfaces is readily apparent in optical microscopy images, as demonstrated by Ke Xu, Michael F. Crommie, Ting Xu, and co-workers in article number 1701536.
      PubDate: 2017-09-21T07:46:40.290076-05:
      DOI: 10.1002/adma.201770262
       
  • Masthead: (Adv. Mater. 36/2017)
    • PubDate: 2017-09-21T07:46:40.203899-05:
      DOI: 10.1002/adma.201770260
       
  • Bioinspired Catalysts: Exceptional High-Performance of Pt-Based Bimetallic
           Catalysts for Exclusive Detection of Exhaled Biomarkers (Adv. Mater.
           36/2017)
    • Authors: Sang-Joon Kim; Seon-Jin Choi, Ji-Soo Jang, Hee-Jin Cho, Won-Tae Koo, Harry L. Tuller, Il-Doo Kim
      Abstract: Nanofibrous semiconductor metal oxides (SMOs) functionalized by Pt-based bimetallic catalysts are synthesized by bioinspired protein templates by Il-Doo Kim and co-workers in article number 1700737. Pt-based bimetallic catalysts such as PtPd, PtRh, and PtNi are uniformly functionalized on the surface of the SMO nanofibers. As a result, exceptionally high sensing performance is achieved by selective detection of the biomarker species, such as acetone and hydrogen sulfide, in exhaled breath with potential application in the diagnosis of diseases by analyzing exhaled human breath.
      PubDate: 2017-09-21T07:46:38.290308-05:
      DOI: 10.1002/adma.201770257
       
  • Wearable Sensors: Supercapacitive Iontronic Nanofabric Sensing (Adv.
           Mater. 36/2017)
    • Authors: Ruya Li; Yang Si, Zijie Zhu, Yaojun Guo, Yingjie Zhang, Ning Pan, Gang Sun, Tingrui Pan
      Abstract: In article number 1700253, Tingrui Pan and co-workers introduce a novel all-fabric supercapacitive sensing modality for wearable pressure and force sensing based on a novel elastic ionic–electronic interface. Utilizing the electrospun iontronic nanofabric as a sensing element, the supercapacitive iontronic fabric offers an unprecedented sensitivity of 114 nF kPa−1, single-Pascal pressure resolution, and millisecond response time, with a high level of noise immunity and signal stability for emerging wearable and medical applications.
      PubDate: 2017-09-21T07:46:38.218369-05:
      DOI: 10.1002/adma.201770264
       
  • Cancer Therapy: Biotransporting Self-Assembled Nanofactories Using Polymer
           Vesicles with Molecular Permeability for Enzyme Prodrug Cancer Therapy
           (Adv. Mater. 36/2017)
    • Authors: Tomoki Nishimura; Yoshihiro Sasaki, Kazunari Akiyoshi
      Abstract: In article number 1702406, Kazunari Akiyoshi and co-workers develop self-assembled nanofactories formulated with intrinsically molecular permeable polymer vesicles. Because of this permeability, enzyme-loaded vesicles act as enzyme reactors, enabling the diffusion of a variety of low-molecular-weight substrates, including clinical prodrugs, to react with the retained encapsulated enzymes in vitro and in vivo. Thus, the vesicles serve as nanofactories that can transform prodrugs into drugs at tumor sites for cancer therapy.
      PubDate: 2017-09-21T07:46:34.640781-05:
      DOI: 10.1002/adma.201770258
       
  • Contents: (Adv. Mater. 36/2017)
    • PubDate: 2017-09-21T07:46:32.370159-05:
      DOI: 10.1002/adma.201770259
       
  • High-Energy-Density Metal–Oxygen Batteries: Lithium–Oxygen Batteries
           vs Sodium–Oxygen Batteries
    • Authors: Kyeongse Song; Daniel Adjei Agyeman, Mihui Park, Junghoon Yang, Yong-Mook Kang
      Abstract: The development of next-generation energy-storage devices with high power, high energy density, and safety is critical for the success of large-scale energy-storage systems (ESSs), such as electric vehicles. Rechargeable sodium–oxygen (Na–O2) batteries offer a new and promising opportunity for low-cost, high-energy-density, and relatively efficient electrochemical systems. Although the specific energy density of the Na–O2 battery is lower than that of the lithium–oxygen (Li–O2) battery, the abundance and low cost of sodium resources offer major advantages for its practical application in the near future. However, little has so far been reported regarding the cell chemistry, to explain the rate-limiting parameters and the corresponding low round-trip efficiency and cycle degradation. Consequently, an elucidation of the reaction mechanism is needed for both lithium–oxygen and sodium–oxygen cells. An in-depth understanding of the differences and similarities between Li–O2 and Na–O2 battery systems, in terms of thermodynamics and a structural viewpoint, will be meaningful to promote the development of advanced metal–oxygen batteries. State-of-the-art battery design principles for high-energy-density lithium–oxygen and sodium–oxygen batteries are thus reviewed in depth here. Major drawbacks, reaction mechanisms, and recent strategies to improve performance are also summarized.Rechargeable metal–air batteries such as lithium–oxygen and sodium–oxygen offer a new and promising opportunity for low-cost, high-energy-density, and relatively efficient electrochemical systems. An in-depth understanding of the differences and similarities between Li–O2 and Na–O2 batteries in terms of thermodynamics and a structural viewpoint is therefore very meaningful to promote the development of advanced metal–oxygen batteries.
      PubDate: 2017-09-21T07:23:29.651885-05:
      DOI: 10.1002/adma.201606572
       
  • Perspective on Structural Evolution and Relations with Thermophysical
           Properties of Metallic Liquids
    • Authors: Xiaodong Wang; Jianzhong Jiang
      Abstract: The relationship between the structural evolution and properties of metallic liquids is a long-standing hot issue in condensed-matter physics and materials science. Here, recent progress is reviewed in several fundamental aspects of metallic liquids, including the methods to study their atomic structures, liquid–liquid transition, physical properties, fragility, and their correlations with local structures, together with potential applications of liquid metals at room temperature. Involved with more experimentally and theoretically advanced techniques, these studies provide more in-depth understanding of the structure–property relationship of metallic liquids and promote the design of new metallic materials with superior properties.Metallic liquids are important substances in scientific research and industrial applications. Recent progress in several fundamental aspects in metallic liquids, mainly focusing on the structural evolution and relations with thermophysical properties, is reviewed. This provides more in-depth understanding of the structure–property relationships of metallic liquids and promotes the design of new metallic materials with superior properties.
      PubDate: 2017-09-21T07:20:50.645559-05:
      DOI: 10.1002/adma.201703136
       
  • Bottom-Up Single-Electron Transistors
    • Authors: Ksenia S. Makarenko; Zhihua Liu, Michel P. de Jong, Floris A. Zwanenburg, Jurriaan Huskens, Wilfred G. van der Wiel
      Abstract: As the downscaling of conventional semiconductor electronics becomes more and more challenging, the interest in alternative material systems and fabrication methods is growing. A novel bottom-up approach for the fabrication of high-quality single-electron transistors (SETs) that can easily be contacted electrically in a controllable manner is developed. This approach employs the self-assembly of Au nanoparticles forming the SETs, and Au nanorods forming the leads to macroscopic electrodes, thus bridging the gap between the nano- and microscale. Low-temperature electron-transport measurements reveal exemplary single-electron tunneling characteristics. SET behavior can be significantly changed, post-fabrication, using molecular exchange of the tunnel barriers, demonstrating the tunability of the assemblies. These results form a promising proof of principle for the versatility of bottom-up nanoelectronics, and toward controlled fabrication of nanoelectronic devices.High-quality single-electron transistors (SETs) are fabricated by a newly developed, novel bottom-up approach. The approach relies on the self-assembly of Au nanoparticles, forming the SETs, and Au nanorods, serving as extended electric leads. The self-assembly is driven by the electrostatic interaction between the tailor-made molecular monolayers on the constituents of the heterogeneous assembly.
      PubDate: 2017-09-18T07:32:02.989629-05:
      DOI: 10.1002/adma.201702920
       
  • Temporal and Remote Tuning of Piezophotonic-Effect-Induced Luminescence
           and Color Gamut via Modulating Magnetic Field
    • Authors: Man-Chung Wong; Li Chen, Gongxun Bai, Long-Biao Huang, Jianhua Hao
      Abstract: Light-emitting materials have been extensively investigated because of their widespread applications in solid-state lighting, displays, sensors, and bioimaging. In these applications, it is highly desirable to achieve tunable luminescence in terms of luminescent intensity and wavelength. Here, a convenient physical approach of temporal and remote tuning of light-emitting wavelength and color is demonstrated, which is greatly different from conventional methods. It is shown that by modulating the frequency of magnetic-field excitation at room temperature, luminescence from the flexible composites of ZnS:Al, Cu phosphors induced by the piezophotonic effect can be tuned in real time and in situ. The mechanistic investigation suggests that the observed tunable piezophotonic emission is ascribed to the tilting band structure of the ZnS phosphor induced by magnetostrictive strain under a high frequency of magnetic-field excitation. Furthermore, some proof-of concept devices, including red–green–blue full-color displays and tunable white-light sources are demonstrated simply by frequency modulation. A new understanding of the fundamentals of both luminescence and magnetic–optics coupling is thus provided, while offering opportunities in magnetic–optical sensing, piezophotonics, energy harvesting, novel light sources, and displays.Temporal tuning of the light-emitting wavelength and color by an in situ and reversible method is presented, which differs greatly from conventional approaches. Red–green–blue and tunable white-light are demonstrated by modulating the frequency of magnetic excitation. A new understanding of the luminescence mechanism is thus determined. The findings will offer opportunities in magnetic–optical sensing, piezophotonics, energy harvesting, novel light sources, and displays.
      PubDate: 2017-09-18T07:31:17.39601-05:0
      DOI: 10.1002/adma.201701945
       
  • Characterization of Edge Contact: Atomically Resolved
           Semiconductor–Metal Lateral Boundary in MoS2
    • Authors: Hyeokshin Kwon; Kiyoung Lee, Jinseong Heo, Youngtek Oh, Hyangsook Lee, Samudrala Appalakondaiah, Wonhee Ko, Hyo Won Kim, Jin-Wook Jung, Hwansoo Suh, Hongki Min, Insu Jeon, Euyheon Hwang, Sungwoo Hwang
      Abstract: Despite recent efforts for the development of transition-metal-dichalcogenide-based high-performance thin-film transistors, device performance has not improved much, mainly because of the high contact resistance at the interface between the 2D semiconductor and the metal electrode. Edge contact has been proposed for the fabrication of a high-quality electrical contact; however, the complete electronic properties for the contact resistance have not been elucidated in detail. Using the scanning tunneling microscopy/spectroscopy and scanning transmission electron microscopy techniques, the edge contact, as well as the lateral boundary between the 2D semiconducting layer and the metalized interfacial layer, are investigated, and their electronic properties and the energy band profile across the boundary are shown. The results demonstrate a possible mechanism for the formation of an ohmic contact in homojunctions of the transition-metal dichalcogenides semiconductor–metal layers and suggest a new device scheme utilizing the low-resistance edge contact.The edge contact and the lateral boundary between a semiconducting layer and a metalized interfacial layer are investigated using scanning tunneling microscopy/spectroscopy and scanning transmission electron microscopy techniques. The electronic properties and the energy band profile across the boundary are shown. A new device scheme based on the low-resistance edge contact is thus provided.
      PubDate: 2017-09-18T07:30:44.247578-05:
      DOI: 10.1002/adma.201702931
       
  • Highly Anisotropic Conductors
    • Authors: Jiayu Wan; Jianwei Song, Zhi Yang, Dylan Kirsch, Chao Jia, Rui Xu, Jiaqi Dai, Mingwei Zhu, Lisha Xu, Chaoji Chen, Yanbin Wang, Yilin Wang, Emily Hitz, Steven D. Lacey, Yongfeng Li, Bao Yang, Liangbing Hu
      Abstract: Composite materials with ordered microstructures often lead to enhanced functionalities that a single material can hardly achieve. Many biomaterials with unusual microstructures can be found in nature; among them, many possess anisotropic and even directional physical and chemical properties. With inspiration from nature, artificial composite materials can be rationally designed to achieve this anisotropic behavior with desired properties. Here, a metallic wood with metal continuously filling the wood vessels is developed, which demonstrates excellent anisotropic electrical, thermal, and mechanical properties. The well-aligned metal rods are confined and separated by the wood vessels, which deliver directional electron transport parallel to the alignment direction. Thus, the novel metallic wood composite boasts an extraordinary anisotropic electrical conductivity (σ /σ⊥) in the order of 1011, and anisotropic thermal conductivity (κ /κ⊥) of 18. These values exceed the highest reported values in existing anisotropic composite materials. The anisotropic functionality of the metallic wood enables it to be used for thermal management applications, such as thermal insulation and thermal dissipation. The highly anisotropic metallic wood serves as an example for further anisotropic materials design; other composite materials with different biotemplates/hosts and fillers can achieve even higher anisotropic ratios, allowing them to be implemented in a variety of applications.Highly anisotropic metallic wood is fabricated by taking advantage of wood's naturally aligned and hierarchically structured channels. This novel metallic wood composite displays anisotropic electrical and thermal conductivity ratios as high as 1011 and 18, respectively. The aeolotropic properties exhibited by metallic wood open opportunities in applications such as thermal management and electronic plants.
      PubDate: 2017-09-18T07:29:06.840528-05:
      DOI: 10.1002/adma.201703331
       
  • A New Passivation Route Leading to Over 8% Efficient PbSe Quantum-Dot
           Solar Cells via Direct Ion Exchange with Perovskite Nanocrystals
    • Authors: Zhilong Zhang; Zihan Chen, Lin Yuan, Weijian Chen, Jianfeng Yang, Bo Wang, Xiaoming Wen, Jianbing Zhang, Long Hu, John A. Stride, Gavin J. Conibeer, Robert J. Patterson, Shujuan Huang
      Abstract: Colloidal quantum dots (QDs) are promising candidate materials for photovoltaics (PV) owing to the tunable bandgap and low-cost solution processability. Lead selenide (PbSe) QDs are particularly attractive to PV applications due to the efficient multiple-exciton generation and carrier transportation. However, surface defects arising from the oxidation of the PbSe QDs have been the major limitation for their development in PV. Here, a new passivation method for chlorinated PbSe QDs via ion exchange with cesium lead halide (Br, I) perovskite nanocrystals is reported. The surface chloride ions on the as-synthesized QDs can be partially exchanged with bromide or iodide ions from the perovskite nanocrystals, hence forming a hybrid halide passivation. Consistent with the improved photoluminescence quantum yield, the champion PV device fabricated with these PbSe QDs achieves a PCE of 8.2%, compared to 7.3% of that fabricated with the untreated QDs. This new method also leads to devices with excellent air-stability, retaining at least 93% of their initial PCEs after being stored in ambient conditions for 57 d. This is considered as the first reported PbSe QD solar cell with a PCE of over 8% to date.PbSe quantum dots (QDs) with robust hybrid halide passivation are obtained via ion exchange with CsPbX3 halide perovskite nanocrystals, resulting in significant improvement in their photoluminescence quantum yield. A champion solar cell fabricated with these passivated PbSe QDs can achieve an efficiency of over 8%, as well as excellent air-stability.
      PubDate: 2017-09-18T07:28:07.00513-05:0
      DOI: 10.1002/adma.201703214
       
  • Conducting-Polymer-Based Materials for Electrochemical Energy Conversion
           and Storage
    • Authors: Jianfeng Wang; Jinrong Wang, Zhuang Kong, Kuilin Lv, Chao Teng, Ying Zhu
      Abstract: To alleviate the current energy crisis and environmental pollution, sustainable and ecofriendly energy conversion and storage systems are urgently needed. Due to their high conductivity, promising catalytic activity, and excellent electrochemical properties, conducting polymers have been attracting intense attention for use in electrochemical energy conversion and storage. Here, the latest advances regarding the utilization of conducting polymers for fuel cells and supercapacitors are introduced. The strategies employed to improve the electrocatalytic and electrochemical performances of conducting-polymer-based materials are presented. In addition, future research endeavors and possible directions for further progress in this field are outlined.Conducting polymers are considered to be promising materials for energy conversion and storage due to their high conductivity, promising catalytic activity, and excellent electrochemical properties. The latest advances in conducting-polymer-based materials for fuel cells and supercapacitors are highlighted, and possible directions for further progress in this fascinating field are discussed.
      PubDate: 2017-09-18T07:27:01.537683-05:
      DOI: 10.1002/adma.201703044
       
  • Highly Conductive and Transparent Large-Area Bilayer Graphene Realized by
           MoCl5 Intercalation
    • Authors: Hiroki Kinoshita; Il Jeon, Mina Maruyama, Kenji Kawahara, Yuri Terao, Dong Ding, Rika Matsumoto, Yutaka Matsuo, Susumu Okada, Hiroki Ago
      Abstract: Bilayer graphene (BLG) comprises a 2D nanospace sandwiched by two parallel graphene sheets that can be used to intercalate molecules or ions for attaining novel functionalities. However, intercalation is mostly demonstrated with small, exfoliated graphene flakes. This study demonstrates intercalation of molybdenum chloride (MoCl5) into a large-area, uniform BLG sheet, which is grown by chemical vapor deposition (CVD). This study reveals that the degree of MoCl5 intercalation strongly depends on the stacking order of the graphene; twist-stacked graphene shows a much higher degree of intercalation than AB-stacked. Density functional theory calculations suggest that weak interlayer coupling in the twist-stacked graphene contributes to the effective intercalation. By selectively synthesizing twist-rich BLG films through control of the CVD conditions, low sheet resistance (83 Ω ▫−1) is realized after MoCl5 intercalation, while maintaining high optical transmittance (≈95%). The low sheet resistance state is relatively stable in air for more than three months. Furthermore, the intercalated BLG film is applied to organic solar cells, realizing a high power conversion efficiency.Intercalation of MoCl5 into large-area bilayer graphene (BLG) grown by chemical vapor deposition is performed. Twist stacking gives a much higher degree of MoCl5 intercalation than AB stacking. A low sheet resistance with high optical transmittance is obtained by using twist-rich BLG. A transparent electrode suitable for use in organic solar cells is developed from this intercalated bilayer.
      PubDate: 2017-09-18T07:26:12.454539-05:
      DOI: 10.1002/adma.201702141
       
  • Highly Sensitive Detection of Protein Biomarkers with Organic
           Electrochemical Transistors
    • Authors: Ying Fu; Naixiang Wang, Anneng Yang, Helen Ka-wai Law, Li Li, Feng Yan
      Abstract: The analysis of protein biomarkers is of great importance in the diagnosis of diseases. Although many convenient and low-cost electrochemical approaches have been extensively investigated, they are not sensitive enough in the detection of protein biomarkers with low concentrations in physiological environments. Here, this study reports a novel organic-electrochemical-transistor-based biosensor that can successfully detect cancer protein biomarkers with ultrahigh sensitivity. The devices are operated by detecting electrochemical activity on gate electrodes, which is dependent on the concentrations of proteins labeled with catalytic nanoprobes. The protein sensors can specifically detect a cancer biomarker, human epidermal growth factor receptor 2, down to the concentration of 10−14 g mL−1, which is several orders of magnitude lower than the detection limits of previously reported electrochemical approaches. Moreover, the devices can successfully differentiate breast cancer cells from normal cells at various concentrations. The ultrahigh sensitivity of the protein sensors is attributed to the inherent amplification function of the organic electrochemical transistors. This work paves a way for developing highly sensitive and low-cost biosensors for the detection of various protein biomarkers in clinical analysis in the future.Novel organic-electrochemical-transistor-based protein sensors that can specifically detect a cancer biomarker, human epidermal growth factor receptor 2, down to a concentration of 10−14 g mL−1 (10−16m), and differentiate breast cancer cells from normal cells at various concentrations are reported. This work paves a way for developing ultrasensitive, low-cost biosensors for the detection of biomarkers in clinical analysis.
      PubDate: 2017-09-18T07:23:42.683842-05:
      DOI: 10.1002/adma.201703787
       
  • Formation of Ni–Fe Mixed Diselenide Nanocages as a Superior Oxygen
           Evolution Electrocatalyst
    • Authors: Jianwei Nai; Yan Lu, Le Yu, Xin Wang, Xiong Wen (David) Lou
      Abstract: Exploring effective electrocatalysts is a crucial requirement for boosting the efficiency of water splitting to obtain clean fuels. Here, a self-templating strategy is reported to synthesize Ni–Fe mixed diselenide cubic nanocages for the electrocatalytic oxygen evolution reaction (OER). The diselenide nanocages are derived from corresponding Prussian-blue analog nanocages, which are first obtained by treating the nanocube precursor with a site-selective ammonia etchant. The resulting Ni–Fe mixed diselenide nanocages perform as a superior OER electrocatalyst, which affords a current density of 10 mA cm−2 at a small overpotential of 240 mV; a high current density, mass activity, and turnover frequency of 100 mA cm−2, 1000 A g−1, and 0.58 s−1, respectively, at the overpotential of 270 mV; a Tafel slope as small as 24 mV dec−1; and excellent stability in alkaline medium.A self-templating strategy is developed to synthesize Ni–Fe diselenide nanocages with the assistance of a site-selective ammonia etchant. With structural and compositional advantages, these unique nanocages exhibit superior electrocatalytic performance for the oxygen evolution reaction in an alkaline medium.
      PubDate: 2017-09-18T07:22:42.038212-05:
      DOI: 10.1002/adma.201703870
       
  • Semiconducting Polymer Nanoparticles for Centimeters-Deep Photoacoustic
           Imaging in the Second Near-Infrared Window
    • Authors: Jiayingzi Wu; Liyan You, Lu Lan, Hyeon Jeong Lee, Saadia T. Chaudhry, Rui Li, Ji-Xin Cheng, Jianguo Mei
      Abstract: Thienoisoindigo-based semiconducting polymer with a strong near-infrared absorbance is synthesized and its water-dispersed nanoparticles (TSPNs) are investigated as a contrast agent for photoacoustic (PA) imaging in the second near-infrared (NIR-II) window (1000–1350 nm). The TSPNs generate a strong PA signal in the NIR-II optical window, where background signals from endogenous contrast agents, including blood and lipid, are at the local minima. By embedding a TSPN-containing tube in chicken-breast tissue, an imaging depth of more than 5 cm at 1064 nm excitation is achieved with a contrast-agent concentration as low as 40 µg mL−1. The TSPNs under the skin or in the tumor are clearly visualized at 1100 and 1300 nm, with negligible interference from the tissue background. TSPN as a PA contrast in the NIR-II window opens new opportunities for biomedical imaging of deep tissues with improved contrast.Thienoisoindigo-based semiconducting polymer nanoparticles with strong absorption between 1000 and 1350 nm are developed for photoacoustic imaging. These nanoparticles enable imaging in centimeters-deep tissue with negligible interference from the tissue background. This work may pave the way to applications of in vivo photoacoustic imaging in theragnosis.
      PubDate: 2017-09-18T07:20:52.097899-05:
      DOI: 10.1002/adma.201703403
       
  • Liquid-Cell Electron Microscopy of Adsorbed Polymers
    • Authors: Kandula Hima Nagamanasa; Huan Wang, Steve Granick
      Abstract: Individual macromolecules of polystyrene sulfonate and poly(ethylene oxide) are visualized with nanometer resolution using transmission electron microscopy (TEM) imaging of aqueous solutions with and without added salt, trapped in liquid pockets between creased graphene sheets. Successful imaging with 0.3 s per frame is enabled by the sluggish mobility of the adsorbed molecules. This study finds, validating others, that an advantage of this graphene liquid-cell approach is apparently to retard sample degradation from incident electrons, in addition to minimizing background scattering because graphene windows are atomically thin. Its new application here to polymers devoid of metal-ion labeling allows the projected sizes and conformational fluctuations of adsorbed molecules and adsorption–desorption events to be analyzed. Confirming the identification of the observed objects, this study reports statistical analysis of datasets of hundreds of images for times up to 100 s, with variation of the chemical makeup of the polymer, the molecular weight of the polymer, and the salt concentration. This observation of discrete polymer molecules in solution environment may be useful generally, as the findings are obtained using an ordinary TEM microscope, whose kind is available to many researchers routinely.Direct real-space investigation of adsorbed polymer dynamics, with single-polymer resolution using conventional transmission electron microscopy (TEM) (transmission liquid microscope) and graphene liquid cell, gives a time series of polymer images which enable statistical analysis of projected sizes, conformational rearrangements, and adsorption dynamics. This demonstrates the capability to image polymers in solution using a conventional TEM.
      PubDate: 2017-09-18T01:05:02.18576-05:0
      DOI: 10.1002/adma.201703555
       
  • Controlling Molecular Doping in Organic Semiconductors
    • Authors: Ian E. Jacobs; Adam J. Moulé
      Abstract: The field of organic electronics thrives on the hope of enabling low-cost, solution-processed electronic devices with mechanical, optoelectronic, and chemical properties not available from inorganic semiconductors. A key to the success of these aspirations is the ability to controllably dope organic semiconductors with high spatial resolution. Here, recent progress in molecular doping of organic semiconductors is summarized, with an emphasis on solution-processed p-type doped polymeric semiconductors. Highlighted topics include how solution-processing techniques can control the distribution, diffusion, and density of dopants within the organic semiconductor, and, in turn, affect the electronic properties of the material. Research in these areas has recently intensified, thanks to advances in chemical synthesis, improved understanding of charged states in organic materials, and a focus on relating fabrication techniques to morphology. Significant disorder in these systems, along with complex interactions between doping and film morphology, is often responsible for charge trapping and low doping efficiency. However, the strong coupling between doping, solubility, and morphology can be harnessed to control crystallinity, create doping gradients, and pattern polymers. These breakthroughs suggest a role for molecular doping not only in device function but also in fabrication—applications beyond those directly analogous to inorganic doping.Strong interactions between molecular dopants and organic semiconductor morphology are often responsible for charge trapping and low doping efficiency. This study reviews how solution-processing techniques can control these interactions and render them useful for engineering diffusion rates, doping gradients, and film topography. These breakthroughs suggest new roles for molecular doping in device fabrication as well as function.
      PubDate: 2017-09-15T13:17:40.525472-05:
      DOI: 10.1002/adma.201703063
       
  • A Review on Organic–Inorganic Halide Perovskite Photodetectors: Device
           Engineering and Fundamental Physics
    • Authors: Mahshid Ahmadi; Ting Wu, Bin Hu
      Abstract: The last eight years (2009–2017) have seen an explosive growth of interest in organic–inorganic halide perovskites in the research communities of photovoltaics and light-emitting diodes. In addition, recent advancements have demonstrated that this type of perovskite has a great potential in the technology of light-signal detection with a comparable performance to commercially available crystalline Si and III–V photodetectors. The contemporary growth of state-of-the-art multifunctional perovskites in the field of light-signal detection has benefited from its outstanding intrinsic optoelectronic properties, including photoinduced polarization, high drift mobilities, and effective charge collection, which are excellent for this application. Photoactive perovskite semiconductors combine effective light absorption, allowing detection of a wide range of electromagnetic waves from ultraviolet and visible, to the near-infrared region, with low-cost solution processability and good photon yield. This class of semiconductor might empower breakthrough photodetector technology in the field of imaging, optical communications, and biomedical sensing. Therefore, here, the focus is specifically on the critical understanding of materials synthesis, design, and engineering for the next-stage development of perovskite photodetectors and highlighting the current challenges in the field, which need to be further studied in the future.The fundamental optoelectrical properties of organic–inorganic perovskites in combination with low-cost solution processability, broad-band absorption, fast response, and high sensitivity make them very attractive candidates for the application in photodetection. However, insightful understanding on materials properties, device engineering, and internal photophysical processes is required to further advance perovskite photodetectors. Perovskite photodetectors are comprehensively reviewed.
      PubDate: 2017-09-14T11:40:36.768348-05:
      DOI: 10.1002/adma.201605242
       
  • Tuning Surface Structure of 3D Nanoporous Gold by Surfactant-Free
           Electrochemical Potential Cycling
    • Authors: Zhili Wang; Shoucong Ning, Pan Liu, Yi Ding, Akihiko Hirata, Takeshi Fujita, Mingwei Chen
      Abstract: 3D dealloyed nanoporous metals have emerged as a new class of catalysts for various chemical and electrochemical reactions. Similar to other heterogeneous catalysts, the surface atomic structure of the nanoporous metal catalysts plays a crucial role in catalytic activity and selectivity. Through surfactant-assisted bottom-up synthesis, the surface-structure modification has been successfully realized in low-dimensional particulate catalysts. However, the surface modification by top-down dealloying has not been well explored for nanoporous metal catalysts. Here, a surfactant-free approach to tailor the surface structure of nanoporous gold by surface relaxation via electrochemical redox cycling is reported. By controlling the scan rates, nanoporous gold with abundant {111} facets or {100} facets can be designed and fabricated with dramatically improved electrocatalysis toward the ethanol oxidation reaction.A surfactant-free potential-cycling approach is developed to tailor the surface structure of 3D nanoporous gold with an abundance of {111} or {100} facets by controlling the scan rates. The {111}-rich sample exhibits dramatically improved electrocatalysis toward the ethanol oxidation reaction in comparison with as-dealloyed conventional nanoporous gold.
      PubDate: 2017-09-14T11:39:48.044852-05:
      DOI: 10.1002/adma.201703601
       
  • Triplet Harvesting from Intramolecular Singlet Fission in Polytetracene
    • Authors: Andrew B. Pun; Samuel N. Sanders, Elango Kumarasamy, Matthew Y. Sfeir, Daniel N. Congreve, Luis M. Campos
      Abstract: Singlet fission (SF), a promising mechanism of multiple exciton generation, has only recently been engineered as a fast, efficient, intramolecular process (iSF). The challenge now lies in designing and optimizing iSF materials that can be practically applied in high-performance optoelectronic devices. However, most of the reported iSF systems, such as those based on donor–acceptor polymers or pentacene, have low triplet energies, which limits their applications. Tetracene-based materials can overcome significant challenges, as the tetracene triplet state is practically useful, ≈1.2 eV. Here, the synthesis and excited state dynamics of a conjugated tetracene homopolymer are studied. This polymer undergoes ultrafast iSF in solution, generating high-energy triplets on a sub-picosecond time scale. Magnetic-field-dependent photocurrent measurements of polytetracene-based devices demonstrate the first example of iSF-generated triplet extraction in devices, exhibiting the potential of iSF materials for use in next-generation devices.A conjugated tetracene homopolymer is synthesized, investigated spectroscopically, and employed as the active layer in photovoltaic devices. Spectroscopic measurements reveal sub-picosecond singlet fission in this material in solution or in films. Films facilitate dissociation of the resulting triplet pairs. Solution-processed devices employing polytetracene achieve singlet-fission-based photocurrent enhancement, but only when the acceptor energy levels are sufficiently low.
      PubDate: 2017-09-14T11:39:32.352255-05:
      DOI: 10.1002/adma.201701416
       
  • Probing Novel Microstructural Evolution Mechanisms in Aluminum Alloys
           Using 4D Nanoscale Characterization
    • Authors: C. Shashank Kaira; V. De Andrade, Sudhanshu S. Singh, C. Kantzos, Antony Kirubanandham, F. De Carlo, Nikhilesh Chawla
      Abstract: Dispersions of nanoscale precipitates in metallic alloys have been known to play a key role in strengthening, by increasing their strain hardenability and providing resistance to deformation. Although these phenomena have been extensively investigated in the last century, the traditional approaches employed in the past have not rendered an authoritative microstructural understanding in such materials. The effect of the precipitates' inherent complex morphology and their 3D spatial distribution on evolution and deformation behavior have often been precluded. This study reports, for the first time, implementation of synchrotron-based hard X-ray nanotomography in Al–Cu alloys to measure kinetics of different nanoscale phases in 3D, and reveals insights behind some of the observed novel phase transformation reactions. The experimental results of the present study reconcile with coarsening models from the Lifshitz–Slyozov–Wagner theory to an unprecedented extent, thereby establishing a new paradigm for thermodynamic analysis of precipitate assemblies. Finally, this study sheds light on the possibilities for establishing new theories for dislocation–particle interactions, based on the limitations of using the Orowan equation in estimating precipitation strengthening.Probing nanoscale, 4D microstructural evolution in aluminum alloys using transmission X-ray microscopy is reported, and the mechanisms behind the observed novel microstructural transformations are discussed. This approach redefines the understanding of aluminum alloys and overcomes shortcomings of most other characterization techniques by enabling measurement of 3D growth kinetics, validation of existing thermodynamic models, and estimation of 3D crystallographic orientation nondestructively.
      PubDate: 2017-09-14T07:46:08.287-05:00
      DOI: 10.1002/adma.201703482
       
  • Superwettability of Gas Bubbles and Its Application: From Bioinspiration
           to Advanced Materials
    • Authors: Cunming Yu; Peipei Zhang, Jingming Wang, Lei Jiang
      Abstract: Gas bubbles in aqueous media are common and inevitable in, for example, agriculture and industrial processes. The behaviors of gas bubbles on solid interfaces, including generation, growth, coalescence, release, transport, and collection, are crucial to gas-bubble-related applications, which are always determined by gas-bubble wettability on solid interfaces. Here, the recent progress regarding the study of interfaces with gas-bubble superwettability in aqueous media, i.e., superaerophilicity and superaerophobicity, is summarized. Some examples illustrate how to design microstructures and chemical compositions to achieve reliable and effective manipulation of gas-bubble wettability on artificial interfaces. These designed interfaces exhibit excellent performance in gas-evolution reactions, gas-adsorption reactions, and directional gas-bubble transportation. Moreover, progress in the theoretical investigation of gas-bubble superwettability is reported. Lastly, some challenges are presented, such as the reliable manipulation of gas-bubble wettability and the establishment of mature theory for exactly and systematically explaining gas-bubble wetting phenomena.Recent progress on interfaces with gas-bubble superwettability in aqueous media, i.e., superaerophilicity and superaerophobicity, is summarized. Some examples are provided with regard to how to design microstructures and chemical compositions to achieve reliable and effective manipulation of gas-bubble wettability on artificial interfaces.
      PubDate: 2017-09-13T13:01:40.753879-05:
      DOI: 10.1002/adma.201703053
       
  • Graphene in the Design and Engineering of Next-Generation Neural
           Interfaces
    • Authors: Kostas Kostarelos; Melissa Vincent, Clement Hebert, Jose A. Garrido
      Abstract: Neural interfaces are becoming a powerful toolkit for clinical interventions requiring stimulation and/or recording of the electrical activity of the nervous system. Active implantable devices offer a promising approach for the treatment of various diseases affecting the central or peripheral nervous systems by electrically stimulating different neuronal structures. All currently used neural interface devices are designed to perform a single function: either record activity or electrically stimulate tissue. Because of their electrical and electrochemical performance and their suitability for integration into flexible devices, graphene-based materials constitute a versatile platform that could help address many of the current challenges in neural interface design. Here, how graphene and other 2D materials possess an array of properties that can enable enhanced functional capabilities for neural interfaces is illustrated. It is emphasized that the technological challenges are similar for all alternative types of materials used in the engineering of neural interface devices, each offering a unique set of advantages and limitations. Graphene and 2D materials can indeed play a commanding role in the efforts toward wider clinical adoption of bioelectronics and electroceuticals.Active implantable devices offer a promising approach for the treatment of various diseases affecting the central or peripheral nervous systems. A concise description of the rationale and realistic expectations of how the set of properties that graphene and other 2D materials offer can be integrated in the next generation of multifunctional neural interface devices is provided.
      PubDate: 2017-09-13T05:05:48.900282-05:
      DOI: 10.1002/adma.201700909
       
  • Hybrid Copper-Nanowire–Reduced-Graphene-Oxide Coatings: A “Green
           Solution” Toward Highly Transparent, Highly Conductive, and Flexible
           Electrodes for (Opto)Electronics
    • Authors: Alessandro Aliprandi; Tiago Moreira, Cosimo Anichini, Marc-Antoine Stoeckel, Matilde Eredia, Ugo Sassi, Matteo Bruna, Carlos Pinheiro, César A. T. Laia, Sara Bonacchi, Paolo Samorì
      Abstract: This study reports a novel green chemistry approach to assemble copper-nanowires/reduced-graphene-oxide hybrid coatings onto inorganic and organic supports. Such films are robust and combine sheet resistances ( 70%) that are rivalling those of indium–tin oxide. These electrodes are suitable for flexible electronic applications as they show a sheet resistance change of
      PubDate: 2017-09-13T01:11:54.613846-05:
      DOI: 10.1002/adma.201703225
       
  • Polar-Electrode-Bridged Electroluminescent Displays: 2D Sensors Remotely
           Communicating Optically
    • Authors: Xiuru Xu; Dan Hu, Lijia Yan, Shaoli Fang, Clifton Shen, Yueh-Lin Loo, Yuan Lin, Carter S. Haines, Na Li, Anvar A. Zakhidov, Hong Meng, Ray H. Baughman, Wei Huang
      Abstract: A novel geometry for electroluminescent devices, which does not require transparent electrodes for electrical input, is demonstrated, theoretically analyzed, and experimentally characterized. Instead of emitting light through a conventional electrode, light emission occurs through a polar liquid or solid and input electrical electrodes are coplanar, rather than stacked in a sandwich configuration. This new device concept is scalable and easily deployed for a range of modular alternating-current-powered electroluminescent light sources and light-emitting sensing devices. The polar-electrode-bridged electroluminescent displays can be used as remotely readable, spatially responsive sensors that emit light in response to the accumulation and distribution of materials on the device surface. Using this device structure, various types of alternating current devices are demonstrated. These include an umbrella that automatically lights up when it rains, a display that emits light from regions touched by human fingers (or painted upon using a mixture of oil and water), and a sensor that lights up differently in different areas to indicate the presence of water and its freezing. This study extends the dual-stack, coplanar-electrode device geometry to provide displays that emit light from a figure drawn on an electroluminescent panel using a graphite pencil.A new geometry is demonstrated for electroluminescent devices, which does not require transparent electrodes for energy input. Instead of emitting light through a conventional electrode, light emission occurs through a polar liquid or solid. These new devices act as remotely readable, spatially responsive sensors that emit light in response to the accumulation and distribution of materials on the device surface.
      PubDate: 2017-09-12T06:57:32.041971-05:
      DOI: 10.1002/adma.201703552
       
  • Nanodroplet-Containing Polymers for Efficient Low-Power Light Upconversion
    • Authors: Roberto Vadrucci; Angelo Monguzzi, Felipe Saenz, Bodo D. Wilts, Yoan C. Simon, Christoph Weder
      Abstract: Sensitized triplet–triplet-annihilation-based photon upconversion (TTA-UC) permits the conversion of light into radiation of higher energy and involves a sequence of photophysical processes between two dyes. In contrast to other upconversion schemes, TTA-UC allows the frequency shifting of low-intensity light, which makes it particularly suitable for solar-energy harvesting technologies. High upconversion yields can be observed for low viscosity solutions of dyes; but, in solid materials, which are better suited for integration in devices, the process is usually less efficient. Here, it is shown that this problem can be solved by using transparent nanodroplet-containing polymers that consist of a continuous polymer matrix and a dispersed liquid phase containing the upconverting dyes. These materials can be accessed by a simple one-step procedure that involves the free-radical polymerization of a microemulsion of hydrophilic monomers, a lipophilic solvent, the upconverting dyes, and a surfactant. Several glassy and rubbery materials are explored and a range of dyes that enable TTA-UC in different spectral regions are utilized. The materials display upconversion efficiencies of up to ≈15%, approaching the performance of optimized oxygen-free reference solutions. The data suggest that the matrix not only serves as mechanically coherent carrier for the upconverting liquid phase, but also provides good protection from atmospheric oxygen.High yields of triplet–triplet-annihilation-based photon upconversion can be observed for solutions of dyes; but, in solid materials, which are better suited for integration in devices, this process is usually less efficient. It is shown that new, easily accessible nanodroplet-containing polymers consisting of a continuous polymer matrix and a dispersed liquid phase doped with dyes approach the performance of oxygen-free reference solutions.
      PubDate: 2017-09-12T06:56:39.079221-05:
      DOI: 10.1002/adma.201702992
       
  • Topological Design of Ultrastrong and Highly Conductive Graphene Films
    • Authors: Yeye Wen; Mingmao Wu, Miao Zhang, Chun Li, Gaoquan Shi
      Abstract: Nacre-like graphene films are prepared by evaporation-induced assembly of graphene oxide dispersions containing small amounts of cellulose nanocrystal (CNC), followed by chemical reduction with hydroiodic acid. CNC induces the formation of wrinkles on graphene sheets, greatly enhancing the mechanical properties of the resultant graphene films. The graphene films deliver an ultrahigh tensile strength of 765 ± 43 MPa (up to 800 MPa in some cases), a large failure strain of 6.22 ± 0.19%, and a superior toughness of 15.64 ± 2.20 MJ m−3, as well as a high electrical conductivity of 1105 ± 17 S cm−1. They have a great potential for applications in flexible electronics because of their combined excellent mechanical and electrical properties.Ultrastrong graphene films can be readily prepared by tailoring the topological structures of reduced graphene oxide sheets within the graphene films. Integrated lightweight, ultrastrength, superior toughness, and high conductivity enable the graphene films to have great potential application in flexible electronics.
      PubDate: 2017-09-11T10:38:24.608599-05:
      DOI: 10.1002/adma.201702831
       
  • Direct Observations of the Formation and Redox-Mediator-Assisted
           Decomposition of Li2O2 in a Liquid-Cell Li–O2 Microbattery by Scanning
           Transmission Electron Microscopy
    • Authors: Chuchu Yang; Jiuhui Han, Pan Liu, Chen Hou, Gang Huang, Takeshi Fujita, Akihiko Hirata, Mingwei Chen
      Abstract: Operando scanning transmission electron microscopy observations of cathodic reactions in a liquid-cell Li–O2 microbattery in the presence of the redox mediator tetrathiafulvalene (TTF) in 1.0 m LiClO4 dissolved dimethyl sulfoxide electrolyte are reported. It is found that the TTF addition does not obviously affect the discharge reaction for the formation of a solid Li2O2 phase. The coarsening of Li2O2 nanoparticles occurs via both conventional Ostwald ripening and nonclassical crystallization by particle attachment. During charging, the oxidation reaction at significantly reduced charge potentials mainly takes place at Li2O2/electrolyte interfaces and has obvious correspondence with the oxidized TTF+ distributions in the electric fields of the charged electrode. This study provides direct evidence that TTF truly plays a role in promoting the decomposition of Li2O2 as a soluble charge-transfer agent between the electrode and the Li2O2.Operando scanning transmission electron microscopy is used to investigate the cathodic reactions in a liquid-cell Li–O2 microbattery in the presence of redox mediators. The real-time and real-space observations provide experimental insights into the solution mechanisms of Li2O2 growth in a dimethyl-sulfoxide-based electrolyte and the working mechanisms of redox mediators as charge-transfer agents between the electrode surfaces and the solid Li2O2 phase.
      PubDate: 2017-09-11T10:38:03.421216-05:
      DOI: 10.1002/adma.201702752
       
  • Metal-Free Carbon Materials for CO2 Electrochemical Reduction
    • Authors: Xiaochuan Duan; Jiantie Xu, Zengxi Wei, Jianmin Ma, Shaojun Guo, Shuangyin Wang, Huakun Liu, Shixue Dou
      Abstract: The rapid increase of the CO2 concentration in the Earth's atmosphere has resulted in numerous environmental issues, such as global warming, ocean acidification, melting of the polar ice, rising sea level, and extinction of species. To search for suitable and capable catalytic systems for CO2 conversion, electrochemical reduction of CO2 (CO2RR) holds great promise. Emerging heterogeneous carbon materials have been considered as promising metal-free electrocatalysts for the CO2RR, owing to their abundant natural resources, tailorable porous structures, resistance to acids and bases, high-temperature stability, and environmental friendliness. They exhibit remarkable CO2RR properties, including catalytic activity, long durability, and high selectivity. Here, various carbon materials (e.g., carbon fibers, carbon nanotubes, graphene, diamond, nanoporous carbon, and graphene dots) with heteroatom doping (e.g., N, S, and B) that can be used as metal-free catalysts for the CO2RR are highlighted. Recent advances regarding the identification of active sites for the CO2RR and the pathway of reduction of CO2 to the final product are comprehensively reviewed. Additionally, the emerging challenges and some perspectives on the development of heteroatom-doped carbon materials as metal-free electrocatalysts for the CO2RR are included.Emerging heterogeneous carbon materials are considered as promising metal-free electrocatalysts for the electrochemical CO2 reduction reaction (CO2RR) with remarkable catalytic activity, long durability, and high selectivity. Various carbon materials with heteroatom doping as metal-free catalysts for the CO2RR are highlighted and recent advances on the identification of active sites for the CO2RR and the pathways for reduction of CO2 to the final product are comprehensively reviewed.
      PubDate: 2017-09-11T10:37:23.90669-05:0
      DOI: 10.1002/adma.201701784
       
  • Shorter Exciton Lifetimes via an External Heavy-Atom Effect: Alleviating
           the Effects of Bimolecular Processes in Organic Light-Emitting Diodes
    • Authors: Markus Einzinger; Tianyu Zhu, Piotr de Silva, Christian Belger, Timothy M. Swager, Troy Van Voorhis, Marc A. Baldo
      Abstract: Multiexcited-state phenomena are believed to be the root cause of two exigent challenges in organic light-emitting diodes; namely, efficiency roll-off and degradation. The development of novel strategies to reduce exciton densities under heavy load is therefore highly desirable. Here, it is shown that triplet exciton lifetimes of thermally activated delayed-fluorescence-emitter molecules can be manipulated in the solid state by exploiting intermolecular interactions. The external heavy-atom effect of brominated host molecules leads to increased spin–orbit coupling, which in turn enhances intersystem crossing rates in the guest molecule. Wave function overlap between the host and the guest is confirmed by combined molecular dynamics and density functional theory calculations. Shorter triplet exciton lifetimes are observed, while high photoluminescence quantum yields and essentially unaltered emission spectra are maintained. A change in the intersystem crossing rate ratio due to increased dielectric constants leads to almost 50% lower triplet exciton densities in the emissive layer in the steady state and results in an improved onset of the photoluminescence quantum yield roll-off at high excitation densities. Efficient organic light-emitting diodes with better roll-off behavior based on these novel hosts are fabricated, demonstrating the suitability of this concept for real-world applications.Brominated hosts with an external heavy-atom effect lead to shorter triplet exciton lifetimes in thermally activated, delayed-fluorescence guest molecules due to increased spin–orbit coupling and intersystem crossing rates. Combined with externally manipulated singlet–triplet splitting of the dopants, this results in enhanced onsets of the photoluminescence quantum yield roll-off and fabrication of organic light-emitting diodes with improved droop behavior.
      PubDate: 2017-09-11T10:35:52.644683-05:
      DOI: 10.1002/adma.201701987
       
  • The Role of Rubidium in Multiple-Cation-Based High-Efficiency Perovskite
           Solar Cells
    • Authors: Pankaj Yadav; M. Ibrahim Dar, Neha Arora, Essa A. Alharbi, Fabrizio Giordano, Shaik Mohammed Zakeeruddin, Michael Grätzel
      Abstract: Perovskite solar cells (PSCs) based on cesium (Cs)- and rubidium (Rb)-containing perovskite films show highly reproducible performance; however, a fundamental understanding of these systems is still emerging. Herein, this study has systematically investigated the role of Cs and Rb cations in complete devices by examining the transport and recombination processes using current–voltage characteristics and impedance spectroscopy in the dark. As the credibility of these measurements depends on the performance of devices, this study has chosen two different PSCs, (MAFACs)Pb(IBr)3 (MA = CH3NH3+, FA = CH(NH2)2+) and (MAFACsRb)Pb(IBr)3, yielding impressive performances of 19.5% and 21.1%, respectively. From detailed studies, this study surmises that the confluence of the low trap-assisted charge-carrier recombination, low resistance offered to holes at the perovskite/2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene interface with a low series resistance (Rs), and low capacitance leads to the realization of higher performance when an extra Rb cation is incorporated into the absorber films. This study provides a thorough understanding of the impact of inorganic cations on the properties and performance of highly efficient devices, and also highlights new strategies to fabricate efficient multiple-cation-based PSCs.The confluence of low trap-assisted charge-carrier recombination, low resistance offered to holes at the perovskite/2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene interface with a low series resistance (RS), and a lower value of charge storage, leads to the realization of higher photovoltaic performance when an extra cation (Rb) is incorporated into the perovskite films.
      PubDate: 2017-09-11T10:35:34.519121-05:
      DOI: 10.1002/adma.201701077
       
  • Roll-to-Roll Production of Transparent Silver-Nanofiber-Network Electrodes
           for Flexible Electrochromic Smart Windows
    • Authors: Sen Lin; Xiaopeng Bai, Haiyang Wang, Haolun Wang, Jianan Song, Kai Huang, Chang Wang, Ning Wang, Bo Li, Ming Lei, Hui Wu
      Abstract: Electrochromic smart windows (ECSWs) are considered as the most promising alternative to traditional dimming devices. However, the electrode technology in ECSWs remains stagnant, wherein inflexible indium tin oxide and fluorine-doped tin oxide are the main materials being used. Although various complicated production methods, such as high-temperature calcination and sputtering, have been reported, the mass production of flexible and transparent electrodes remains challenging. Here, a nonheated roll-to-roll process is developed for the continuous production of flexible, extralarge, and transparent silver nanofiber (AgNF) network electrodes. The optical and mechanical properties, as well as the electrical conductivity of these products (i.e., 12 Ω sq−1 at 95% transmittance) are comparable with those AgNF networks produced via high-temperature sintering. Moreover, the as-prepared AgNF network is successfully assembled into an A4-sized ECSW with short switching time, good coloration efficiency, and flexibility.Flexible and transparent electrodes are attracting increasing attention with important applications for various fields. However, the mass production of large-area electrodes has always been a challenge. A roll-to-roll process is proposed to assemble flexible, extralarge, and transparent Ag-nanofiber-network electrodes with good photoelectric properties (≈12 Ω sq−1 at 95% transmittance) for new-generation flexible electronics such as electrochromic smart windows.
      PubDate: 2017-09-11T10:34:18.432073-05:
      DOI: 10.1002/adma.201703238
       
  • Self-Assembly of an Amphiphilic Janus Camptothecin–Floxuridine Conjugate
           into Liposome-Like Nanocapsules for More Efficacious Combination
           Chemotherapy in Cancer
    • Authors: Xiaolong Liang; Chuang Gao, Ligang Cui, Shumin Wang, Jinrui Wang, Zhifei Dai
      Abstract: The combination of camptothecin (CPT) and fluoropyrimidine derivatives acts synergistically at a 1:1 molar ratio. Practically, the greatest challenge is the development of a single liposomal formulation that can both encapsulate and maintain this drug combination at an exact 1:1 ratio to achieve coordinated pharmacokinetics. Consequently, a new type of liposome-like nanocapsule (NC) is developed from a highly symmetric Janus camptothecin–floxuridine conjugate (JCFC) amphiphile, which is synthesized by coupling two hydrophobic CPT molecules and two hydrophilic floxuridine (FUDR) molecules to multivalent pentaerythritol via a hydrolyzable ester linkage. JCFC NCs possess remarkably high drug-loading contents, and no premature release because of the highly stable co-delivery of the drug combination without the need for any carrier. It is shown that JCFC NCs consistently provide synergy and avoid antagonism in a broad panel of tumor cell lines. In vivo delivery of JCFC NCs leads to longer blood retention half-life, higher tumorous accumulation and cellular uptake of drugs, and greatly enhanced efficacy in murine tumor models compared to CPT, FUDR, and CPT + FUDR. This liposomal strategy can be extended to other hydrophilic and hydrophobic anticancer drugs that are coupled to pentaerythritol to self-assemble into nanocapsules for drug self-delivery, pointing to potential clinical translation in near future.Novel liposome-like nanocapsules (NCs) are successfully developed from a highly symmetric Janus camptothecin–floxuridine conjugate (JCFC) amphiphile. JCFC NCs can deliver and preserve a fixed 1:1 molar ratio of the two drugs in a liposomal manner that can suppress premature burst release and coordinate the pharmacokinetics of different drugs after administration, thus resulting in higher apoptotic rate and synergetic anticancer activity.
      PubDate: 2017-09-11T01:37:53.409298-05:
      DOI: 10.1002/adma.201703135
       
  • Stable Li Metal Anodes via Regulating Lithium Plating/Stripping in
           Vertically Aligned Microchannels
    • Authors: Shu-Hua Wang; Ya-Xia Yin, Tong-Tong Zuo, Wei Dong, Jin-Yi Li, Ji-Lei Shi, Chang-Huan Zhang, Nian-Wu Li, Cong-Ju Li, Yu-Guo Guo
      Abstract: Li anodes have been rapidly developed in recent years owing to the rising demand for higher-energy-density batteries. However, the safety issues induced by dendrites hinder the practical applications of Li anodes. Here, Li metal anodes stabilized by regulating lithium plating/stripping in vertically aligned microchannels are reported. The current density distribution and morphology evolution of the Li deposits on porous Cu current collectors are systematically analyzed. Based on simulations in COMSOL Multiphysics, the tip effect leads to preferential deposition on the microchannel walls, thus taking full advantage of the lightening rod theory of classical electromagnetism for restraining growth of Li dendrites. The Li anode with a porous Cu current collector achieves an enhanced cycle stability and a higher average Coulombic efficiency of 98.5% within 200 cycles. In addition, the resultant LiFePO4/Li full battery demonstrates excellent rate capability and stable cycling performance, thus demonstrating promise as a current collector for high-energy-density, safe rechargeable Li batteries.A new strategy to restrain lithium dendrite growth is proposed and demonstrated using vertically aligned microchannel Cu current collectors for Li metal anodes. Most of the lithium is preferentially deposited into the microchannels. The current-density distribution, deposition behavior, and electrochemical performance are simulated and investigated experimentally to understand the effectiveness of the microchannel structure.
      PubDate: 2017-09-11T01:37:07.383618-05:
      DOI: 10.1002/adma.201703729
       
  • Tailoring Semiconductor Lateral Multijunctions for Giant Photoconductivity
           Enhancement
    • Authors: Yutsung Tsai; Zhaodong Chu, Yimo Han, Chih-Piao Chuu, Di Wu, Alex Johnson, Fei Cheng, Mei-Yin Chou, David A. Muller, Xiaoqin Li, Keji Lai, Chih-Kang Shih
      Abstract: Semiconductor heterostructures have played a critical role as the enabler for new science and technology. The emergence of transition-metal dichalcogenides (TMDs) as atomically thin semiconductors has opened new frontiers in semiconductor heterostructures either by stacking different TMDs to form vertical heterojunctions or by stitching them laterally to form lateral heterojunctions via direct growth. In conventional semiconductor heterostructures, the design of multijunctions is critical to achieve carrier confinement. Analogously, successful synthesis of a monolayer WS2/WS2(1−x)Se2x/WS2 multijunction lateral heterostructure via direct growth by chemical vapor deposition is reported. The grown structures are characterized by Raman, photoluminescence, and annular dark-field scanning transmission electron microscopy to determine their lateral compositional profile. More importantly, using microwave impedance microscopy, it is demonstrated that the local photoconductivity in the alloy region can be tailored and enhanced by two orders of magnitude over pure WS2. Finite element analysis confirms that this effect is due to the carrier diffusion and confinement into the alloy region. This work exemplifies the technological potential of atomically thin lateral heterostructures in optoelectronic applications.The successful synthesis of a monolayer lateral heterostructure with multijunctions WS2/WS2(1−x)Se2x/WS2 (x ≈ 0.15) by chemical vapor deposition is reported. The grown structures are characterized by Raman and photoluminescence. Using light-assisted microwave impedance microscopy, the multijunctions demonstrate that the local photoconductivity in the alloy region can be tailored and enhanced by two orders of magnitude over pure WS2.
      PubDate: 2017-09-11T01:36:19.912392-05:
      DOI: 10.1002/adma.201703680
       
  • Wearable Large-Scale Perovskite Solar-Power Source via Nanocellular
           Scaffold
    • Authors: Xiaotian Hu; Zengqi Huang, Xue Zhou, Pengwei Li, Yang Wang, Zhandong Huang, Meng Su, Wanjie Ren, Fengyu Li, Mingzhu Li, Yiwang Chen, Yanlin Song
      Abstract: Dramatic advances in perovskite solar cells (PSCs) and the blossoming of wearable electronics have triggered tremendous demands for flexible solar-power sources. However, the fracturing of functional crystalline films and transmittance wastage from flexible substrates are critical challenges to approaching the high-performance PSCs with flexural endurance. In this work, a nanocellular scaffold is introduced to architect a mechanics buffer layer and optics resonant cavity. The nanocellular scaffold releases mechanical stresses during flexural experiences and significantly improves the crystalline quality of the perovskite films. The nanocellular optics resonant cavity optimizes light harvesting and charge transportation of devices. More importantly, these flexible PSCs, which demonstrate excellent performance and mechanical stability, are practically fabricated in modules as a wearable solar-power source. A power conversion efficiency of 12.32% for a flexible large-scale device (polyethylene terephthalate substrate, indium tin oxide-free, 1.01 cm2) is achieved. This ingenious flexible structure will enable a new approach for development of wearable electronics.A nanocellular scaffold is introduced to construct a mechanics buffer layer and optics resonant cavity in a flexible perovskite solar cell. A power conversion efficiency of 12.32% is achieved with a flexible, large-scale device (polyethylene terephthalate substrate, indium tin oxide-free, 1.01 cm2). Moreover, the devices, which demonstrate excellent performance and mechanical stability, are practically fabricated in modules for a wearable solar-power source.
      PubDate: 2017-09-08T07:54:07.666437-05:
      DOI: 10.1002/adma.201703236
       
  • Liquid Quinones for Solvent-Free Redox Flow Batteries
    • Authors: Akihiro Shimizu; Keisuke Takenaka, Naoyuki Handa, Toshiki Nokami, Toshiyuki Itoh, Jun-Ichi Yoshida
      Abstract: Liquid benzoquinone and naphthoquinone having diethylene glycol monomethyl ether groups are designed and synthesized as redox active materials that dissolve supporting electrolytes. The Li-ion batteries based on the liquid quinones using LiBF4/PC show good performance in terms of voltage, capacity, energy efficiency, and cyclability in both static and flow modes. A battery is constructed without using intentionally added organic solvent, and its high energy density (264 W h L−1) demonstrates the potential of solvent-free organic redox flow batteries using liquid active materials.Liquid benzoquinone and naphthoquinone having diethylene glycol monomethyl ether groups are designed and synthesized as redox active materials that dissolve supporting electrolytes. A battery is constructed without using intentionally added organic solvent, and its high energy density (264 W h L−1) demonstrates the potential of organic redox flow batteries using liquid active materials.
      PubDate: 2017-09-08T07:50:36.619408-05:
      DOI: 10.1002/adma.201606592
       
  • Hybrid 3D Printing of Soft Electronics
    • Authors: Alexander D. Valentine; Travis A. Busbee, John William Boley, Jordan R. Raney, Alex Chortos, Arda Kotikian, John Daniel Berrigan, Michael F. Durstock, Jennifer A. Lewis
      Abstract: Hybrid 3D printing is a new method for producing soft electronics that combines direct ink writing of conductive and dielectric elastomeric materials with automated pick-and-place of surface mount electronic components within an integrated additive manufacturing platform. Using this approach, insulating matrix and conductive electrode inks are directly printed in specific layouts. Passive and active electrical components are then integrated to produce the desired electronic circuitry by using an empty nozzle (in vacuum-on mode) to pick up individual components, place them onto the substrate, and then deposit them (in vacuum-off mode) in the desired location. The components are then interconnected via printed conductive traces to yield soft electronic devices that may find potential application in wearable electronics, soft robotics, and biomedical devices.Hybrid 3D printing combines direct writing of stretchable conductive traces (electrodes) and elastomeric matrices with automated pick and place of surface mount electrical components, e.g., light-emitting diodes, to create soft electronic devices, such as wearable sensors.
      PubDate: 2017-09-06T02:00:02.096952-05:
      DOI: 10.1002/adma.201703817
       
  • A Eutectic Mixture of Natural Fatty Acids Can Serve as the Gating Material
           for Near-Infrared-Triggered Drug Release
    • Authors: Chunlei Zhu; Da Huo, Qiaoshan Chen, Jiajia Xue, Song Shen, Younan Xia
      Abstract: A smart release system responsive to near-infrared (NIR) light is developed for intracellular drug delivery. The concept is demonstrated by coencapsulating doxorubicin (DOX) (an anticancer drug) and IR780 iodide (IR780) (an NIR-absorbing dye) into nanoparticles made of a eutectic mixture of naturally occurring fatty acids. The eutectic mixture has a well-defined melting point at 39 °C, and can be used as a biocompatible phase-change material for NIR-triggered drug release. The resultant nanoparticles exhibit prominent photothermal effect and quick drug release in response to NIR irradiation. Fluorescence microscopy analysis indicates that the DOX trapped in the nanoparticles can be efficiently released into the cytosol under NIR irradiation, resulting in enhanced anticancer activity. A new platform is thus offered for designing effective intracellular drug-release systems, holding great promise for future cancer therapy.A smart system responsive to near-infrared (NIR) light is developed by coencapsulating a drug and an NIR-absorbing dye into nanoparticles made of a eutectic mixture of naturally occurring fatty acids. Photothermal heating under NIR irradiation facilitates rapid and efficient intracellular drug release, leading to enhancement in anticancer activity.
      PubDate: 2017-09-05T07:26:45.571094-05:
      DOI: 10.1002/adma.201703702
       
  • Nanolattices: An Emerging Class of Mechanical Metamaterials
    • Authors: Jens Bauer; Lucas R. Meza, Tobias A. Schaedler, Ruth Schwaiger, Xiaoyu Zheng, Lorenzo Valdevit
      Abstract: In 1903, Alexander Graham Bell developed a design principle to generate lightweight, mechanically robust lattice structures based on triangular cells; this has since found broad application in lightweight design. Over one hundred years later, the same principle is being used in the fabrication of nanolattice materials, namely lattice structures composed of nanoscale constituents. Taking advantage of the size-dependent properties typical of nanoparticles, nanowires, and thin films, nanolattices redefine the limits of the accessible material-property space throughout different disciplines. Herein, the exceptional mechanical performance of nanolattices, including their ultrahigh strength, damage tolerance, and stiffness, are reviewed, and their potential for multifunctional applications beyond mechanics is examined. The efficient integration of architecture and size-affected properties is key to further develop nanolattices. The introduction of a hierarchical architecture is an effective tool in enhancing mechanical properties, and the eventual goal of nanolattice design may be to replicate the intricate hierarchies and functionalities observed in biological materials. Additive manufacturing and self-assembly techniques enable lattice design at the nanoscale; the scaling-up of nanolattice fabrication is currently the major challenge to their widespread use in technological applications.Nanolattices are highly ordered three-dimensional architectures composed of nanoscale constituents, and have, in the recent past, redefined the limits of the accessible material-property space throughout different disciplines. The exceptional mechanical properties of nanolattices, including their ultrahigh strength, damage tolerance, and stiffness, are reviewed, and their potential for multifunctional applications beyond mechanics, relevant fabrication methods, and future directions are discussed.
      PubDate: 2017-09-05T07:26:27.14938-05:0
      DOI: 10.1002/adma.201701850
       
  • Hollow-Structured Graphene–Silicone-Composite-Based Piezoresistive
           Sensors: Decoupled Property Tuning and Bending Reliability
    • Authors: Ningqi Luo; Yan Huang, Jing Liu, Shih-Chi Chen, Ching Ping Wong, Ni Zhao
      Abstract: A versatile flexible piezoresistive sensor should maintain high sensitivity in a wide linear range, and provide a stable and repeatable pressure reading under bending. These properties are often difficult to achieve simultaneously with conventional filler–matrix composite active materials, as tuning of one material component often results in change of multiple sensor properties. Here, a material strategy is developed to realize a 3D graphene–poly(dimethylsiloxane) hollow structure, where the electrical conductivity and mechanical elasticity of the composite can be tuned separately by varying the graphene layer number and the poly(dimethylsiloxane) composition ratio, respectively. As a result, the sensor sensitivity and linear range can be easily improved through a decoupled tuning process, reaching a sensitivity of 15.9 kPa−1 in a 60 kPa linear region, and the sensor also exhibits fast response (1.2 ms rising time) and high stability. Furthermore, by optimizing the density of the graphene percolation network and thickness of the composite, the stability and repeatability of the sensor output under bending are improved, achieving a measurement error below 6% under bending radius variations from −25 to +25 mm. Finally, the potential applications of these sensors in wearable medical devices and robotic vision are explored.A 3D graphene–poly(dimethylsiloxane) hollow-structured composite is developed to independently tune the electrical and mechanical properties of the composite, thus allowing simultaneous improvement of both the sensitivity and linear range of the composite-based piezoresistive sensor. High reliability and repeatability of the sensor output under bending are achieved by optimizing the density of the percolation network and thickness of the hollow structure.
      PubDate: 2017-09-05T07:16:51.758461-05:
      DOI: 10.1002/adma.201702675
       
  • Ultrahigh-Efficiency Green PHOLEDs with a Voltage under 3 V and a Power
           Efficiency of Nearly 110 lm W−1 at Luminance of 10 000 cd m−2
    • Authors: Dongdong Zhang; Juan Qiao, Deqiang Zhang, Lian Duan
      Abstract: Maintaining high power efficiency (PE) under high brightness is still a pressing problem for the practical application of organic light-emitting diodes (OLEDs). Here, ultrahigh-efficiency green phosphorescent OLEDs (PHOLEDs) with a record-low voltage at luminance above 5000 cd m−2 are fabricated, by developing a novel anthracene/pyridine derivative as the electron-transporting material (ETM) combined with a material displaying thermally activated delayed fluorescence as the host. The pyridine units of the ETM not only facilitate charge injection, but also enhance the electron-transporting mobility, profiting from the closely packed molecules caused by the intermolecular H-bonding. The optimized green PHOLEDs show record-low driving voltages of 2.76 and 2.92 V, with EQEs/PEs of 28.0%/102 lm W−1 and 27.9%/97 lm W−1 at 5000 and 10 000 cd m−2, respectively. Furthermore, device optimization exhibits an unprecedented high PE of 109 lm W−1 at 10 000 cd m−2 with voltage under 3 V. Those values are the state-of-the-art among all reported green OLEDs so far, paving their way toward practical applications.Ultrahigh-efficiencygreen phosphorescent organic light-emitting diodes (PHOLEDs) with a voltage under 3 V and a power efficiency of nearly 110 lm W−1 at a luminance of 10 000 cd m−2 are developed by utilizing a novel anthracene/pyridine derivative as the electron-transporting material combined with a material displaying thermally activated delayed fluorescence as the host.
      PubDate: 2017-09-05T07:15:46.811809-05:
      DOI: 10.1002/adma.201702847
       
  • Bioinspired Redox-Active Catechol-Bearing Polymers as Ultrarobust Organic
           Cathodes for Lithium Storage
    • Authors: Nagaraj Patil; Abdelhafid Aqil, Farid Ouhib, Shimelis Admassie, Olle Inganäs, Christine Jérôme, Christophe Detrembleur
      Abstract: Redox-active catechols are bioinspired precursors for ortho-quinones that are characterized by higher discharge potentials than para-quinones, the latter being extensively used as organic cathode materials for lithium ion batteries (LIBs). Here, this study demonstrates that the rational molecular design of copolymers bearing catechol- and Li+ ion-conducting anionic pendants endow redox-active polymers (RAPs) with ultrarobust electrochemical energy storage features when combined to carbon nanotubes as a flexible, binder-, and metal current collector-free buckypaper electrode. The importance of the structure and functionality of the RAPs on the battery performances in LIBs is discussed. The structure-optimized RAPs can store high-capacities of 360 mA h g−1 at 5C and 320 mA h g−1 at 30C in LIBs. The high ion and electron mobilities within the buckypaper also enable to register 96 mA h g−1 (24% capacity retention) at an extreme C-rate of 600C (6 s for total discharge). Moreover, excellent cyclability is noted with a capacity retention of 98% over 3400 cycles at 30C. The high capacity, superior active-material utilization, ultralong cyclability, and excellent rate performances of RAPs-based electrode clearly rival most of the state-of-the-art Li+ ion organic cathodes, and opens up new horizons for large-scalable fabrication of electrode materials for ultrarobust Li storage.The facile combination of copolymers bearing redox-active catechols and Li+ ion conducting groups with carbon nanotubes provides flexible, binder-, and metal current collector-free buckypaper composite cathodes for Li storage. Their high-capacity, ultralong cyclability, and excellent rate performances may open up new horizons in developing an economical and environmentally benign platform for large-scalable fabrication of electrode materials for ultrarobust Li storage.
      PubDate: 2017-09-04T07:46:06.21912-05:0
      DOI: 10.1002/adma.201703373
       
  • Highly Stretchable, Compliant, Polymeric Microelectrode Arrays for In Vivo
           Electrophysiological Interfacing
    • Authors: Dianpeng Qi; Zhiyuan Liu, Yan Liu, Ying Jiang, Wan Ru Leow, Mayank Pal, Shaowu Pan, Hui Yang, Yu Wang, Xiaoqian Zhang, Jiancan Yu, Bin Li, Zhe Yu, Wei Wang, Xiaodong Chen
      Abstract: Polymeric microelectrode arrays (MEAs) are emerging as a new generation of biointegrated microelectrodes to transduce original electrochemical signals in living tissues to external electrical circuits, and vice versa. So far, the challenge of stretchable polymeric MEAs lies in the competition between high stretchability and good electrode–substrate adhesion. The larger the stretchability, the easier the delamination of electrodes from the substrate due to the mismatch in their Young's modulus. In this work, polypyrrole (PPy) electrode materials are designed, with PPy nanowires integrated on the high conductive PPy electrode arrays. By utilizing this electrode material, for the first time, stretchable polymeric MEAs are fabricated with both high stretchability (≈100%) and good electrode–substrate adhesion (1.9 MPa). In addition, low Young's modulus (450 kPa), excellent recycling stability (10 000 cycles of stretch), and high conductivity of the MEAs are also achieved. As a proof of concept, the as-prepared polymeric MEAs are successfully used for conformally recording the electrocorticograph signals from rats in normal and epileptic states, respectively. Further, these polymeric MEAs are also successful in stimulating the ischiadic nerve of the rat. This strategy provides a new perspective to the highly stretchable and mechanically stable polymeric MEAs, which are vital for compliant neural electrodes.Compliant polymeric microelectrode arrays (MEAs) with both high stretchability and enhanced electrode–substrate adhesion are fabricated by taking advantage of wavy-structured electrodes and nanowire-based transition layers. Additionally, good recycling stability and high conductivity are also achieved. Finally, the as-prepared stretchable polymeric MEAs are successfully implanted for neural recording and stimulation.
      PubDate: 2017-09-04T07:42:03.810902-05:
      DOI: 10.1002/adma.201702800
       
  • Direct Imaging of Superwetting Behavior on Solid–Liquid–Vapor
           Triphase Interfaces
    • Authors: Yun Peng; Xu Jin, Yongmei Zheng, Dong Han, Kesong Liu, Lei Jiang
      Abstract: A solid–liquid–vapor interface dominated by a three-phase contact line usually serves as an active area for interfacial reactions and provides a vital clue to surface behavior. Recently, direct imaging of the triphase interface of superwetting interfaces on the microscale/nanoscale has attracted broad scientific attention for both theoretical research and practical applications, and has gradually become an efficient and intuitive approach to explore the wetting behaviors of various multiphase interfaces. Here, recent progress on characterizing the solid–liquid–vapor triphase interface on the microscale/nanoscale with diverse types of imaging apparatus is summarized. Moreover, the accurate, visible, and quantitative information that can be obtained shows the real interfacial morphology of the wetting behaviors of multiphase interfaces. On the basis of fundamental research, technical innovations in imaging and complicated multiphase interfaces of the superwetting surface are also briefly presented.The solid–liquid–vapor interface, dominated by a three-phase contact line, usually serves as an active area of interfacial reactions and provides vital insight into surface behaviors. Direct imaging of solid–liquid–vapor triphase interfaces at the micro-/nanoscale are efficient approaches for understanding wetting behaviors. Recent progress on characterization techniques of solid–liquid–vapor interface systems at the microscale/nanoscale is summarized.
      PubDate: 2017-09-04T07:41:27.400727-05:
      DOI: 10.1002/adma.201703009
       
  • Self-Powered Pulse Sensor for Antidiastole of Cardiovascular Disease
    • Authors: Han Ouyang; Jingjing Tian, Guanglong Sun, Yang Zou, Zhuo Liu, Hu Li, Luming Zhao, Bojing Shi, Yubo Fan, Yifan Fan, Zhong Lin Wang, Zhou Li
      Abstract: Cardiovascular diseases are the leading cause of death globally; fortunately, 90% of cardiovascular diseases are preventable by long-term monitoring of physiological signals. Stable, ultralow power consumption, and high-sensitivity sensors are significant for miniaturized wearable physiological signal monitoring systems. Here, this study proposes a flexible self-powered ultrasensitive pulse sensor (SUPS) based on triboelectric active sensor with excellent output performance (1.52 V), high peak signal-noise ratio (45 dB), long-term performance (107 cycles), and low cost price. Attributed to the crucial features of acquiring easy-processed pulse waveform, which is consistent with second derivative of signal from conventional pulse sensor, SUPS can be integrated with a bluetooth chip to provide accurate, wireless, and real-time monitoring of pulse signals of cardiovascular system on a smart phone/PC. Antidiastole of coronary heart disease, atrial septal defect, and atrial fibrillation are made, and the arrhythmia (atrial fibrillation) is indicative diagnosed from health, by characteristic exponent analysis of pulse signals accessed from volunteer patients. This SUPS is expected to be applied in self-powered, wearable intelligent mobile diagnosis of cardiovascular disease in the future.A flexible self-powered ultrasensitive pulse sensor (SUPS) based on a triboelectric active sensor is proposed. SUPS can provide accurate, wireless, and real-time monitoring of pulse signals of cardiovascular system on a smart phone/PC. Different types of cardiovascular patients are indicative diagnosed from health. This SUPS is expected to be applied in intelligent mobile diagnosis of cardiovascular disease in the future.
      PubDate: 2017-09-01T14:38:27.34025-05:0
      DOI: 10.1002/adma.201703456
       
  • Ultrasensitive and Fast All-Inorganic Perovskite-Based Photodetector via
           Fast Carrier Diffusion
    • Authors: Bin Yang; Fengying Zhang, Junsheng Chen, Songqiu Yang, Xusheng Xia, Tõnu Pullerits, Weiqiao Deng, Keli Han
      Abstract: Low trap-state density, high carrier mobility, and efficient charge carrier collection are key parameters for photodetectors with high sensitivity and fast response time. This study demonstrates a simple solution growth method to prepare CsPbBr3 microcrystals (MCs) with low trap-state density. Time-dependent photoluminescence study with one-photon excitation (OPE) and two-photon excitation (TPE) indicates that CsPbBr3 MCs exhibit fast carrier diffusion with carrier mobility over 100 cm2 V−1 S−1. Furthermore, CsPbBr3 MC-based photodetectors with high charge carriers' collection efficiency are fabricated. Such photodetectors show ultrahigh responsivity (R) up to 6 × 104 A W−1 with OPE and high R up to 6 A W−1 with TPE. The R for OPE is over one order of magnitude higher (the R for TPE is three orders of magnitude higher) than that of previously reported all-inorganic perovskite-based photodetectors. Moreover, the photodetectors exhibit fast response time of ≈1 ms, which corresponds to a gain ≈105 and a gain- bandwidth product of 108 Hz for OPE (a gain ≈103 and a gain-bandwidth product of 106 Hz for TPE).CsPbBr3 microcrystal (MC)-based photodetectors exhibit ultrahigh responsivity (R) up to 6 × 104 A W−1 with one-photon excitation and R = 6 A W−1 with two-photon excitation. The photodetectors also exhibit fast response time of ≈1 ms. The sensitive and fast photoresponse is ascribed to the large absorption coefficient, low trap-state density, and high carrier mobility of CsPbBr3 MCs.
      PubDate: 2017-09-01T14:36:42.652114-05:
      DOI: 10.1002/adma.201703758
       
  • The Functional Response of Mesenchymal Stem Cells to Electron-Beam
           Patterned Elastomeric Surfaces Presenting Micrometer to Nanoscale
           Heterogeneous Rigidity
    • Authors: Manus J. P. Biggs; Marc Fernandez, Dilip Thomas, Ryan Cooper, Matteo Palma, Jinyu Liao, Teresa Fazio, Carl Dahlberg, Helen Wheadon, Anuradha Pallipurath, Abhay Pandit, Jeffrey Kysar, Shalom J. Wind
      Abstract: Cells directly probe and respond to the physicomechanical properties of their extracellular environment, a dynamic process which has been shown to play a key role in regulating both cellular adhesive processes and differential cellular function. Recent studies indicate that stem cells show lineage-specific differentiation when cultured on substrates approximating the stiffness profiles of specific tissues. Although tissues are associated with a range of Young's modulus values for bulk rigidity, at the subcellular level, tissues are comprised of heterogeneous distributions of rigidity. Lithographic processes have been widely explored in cell biology for the generation of analytical substrates to probe cellular physicomechanical responses. In this work, it is shown for the first time that that direct-write e-beam exposure can significantly alter the rigidity of elastomeric poly(dimethylsiloxane) substrates and a new class of 2D elastomeric substrates with controlled patterned rigidity ranging from the micrometer to the nanoscale is described. The mechanoresponse of human mesenchymal stem cells to e-beam patterned substrates was subsequently probed in vitro and significant modulation of focal adhesion formation and osteochondral lineage commitment was observed as a function of both feature diameter and rigidity, establishing the groundwork for a new generation of biomimetic material interfaces.Cellular rigidity-sensing mechanisms in response to discrete areas of modulated rigidity are not understood. Here, a new class of biomimetic surfaces comprising micro to nanopatterned rigidity by focused electron beam exposure is described. Heterogeneous rigidity substrates induced significant changes to focal adhesion colocalization and osteochondral function in mesenchymal stem cell populations as a function of spot size and spot rigidity.
      PubDate: 2017-09-01T01:03:38.588045-05:
      DOI: 10.1002/adma.201702119
       
  • Half-Metallic Behavior in 2D Transition Metal Dichalcogenides Nanosheets
           by Dual-Native-Defects Engineering
    • Authors: Yun Tong; Yuqiao Guo, Kejun Mu, Huan Shan, Jun Dai, Yi Liu, Zhe Sun, Aidi Zhao, Xiao Cheng Zeng, Changzheng Wu, Yi Xie
      Abstract: Two-dimensional transition metal dichalcogenides (TMDs) have been regarded as one of the best nonartificial low-dimensional building blocks for developing spintronic nanodevices. However, the lack of spin polarization in the vicinity of the Fermi surface and local magnetic moment in pristine TMDs has greatly hampered the exploitation of magnetotransport properties. Herein, a half-metallic structure of TMDs is successfully developed by a simple chemical defect-engineering strategy. Dual native defects decorate titanium diselenides with the coexistence of metal-Ti-atom incorporation and Se-anion defects, resulting in a high-spin-polarized current and local magnetic moment of 2D Ti-based TMDs toward half-metallic room-temperature ferromagnetism character. Arising from spin-polarization transport, the as-obtained T-TiSe1.8 nanosheets exhibit a large negative magnetoresistance phenomenon with a value of −40% (5T, 10 K), representing one of the highest negative magnetoresistance effects among TMDs. It is anticipated that this dual regulation strategy will be a powerful tool for optimizing the intrinsic physical properties of TMD systems.A dual-native-defects (Ti atom self-doping and Se defects) engineering strategy is proposed to introduce a spin polarized current and local magnetic moment into 2D nonmagnetic TiSe2, bringing half-metallic behavior with larger negative magnetoresistance.
      PubDate: 2017-09-01T01:02:56.084228-05:
      DOI: 10.1002/adma.201703123
       
  • Highly Concentrated, Ultrathin Nickel Hydroxide Nanosheet Ink for Wearable
           Energy Storage Devices
    • Authors: Peipei Shi; Rong Chen, Li Hua, Li Li, Ruyi Chen, Yujiao Gong, Chenyang Yu, Jinyuan Zhou, Bin Liu, Gengzhi Sun, Wei Huang
      Abstract: Solution-based techniques are considered as a promising strategy for scalable fabrication of flexible electronics owing to their low-cost and high processing speed. The key to the success of these techniques is dominated by the ink formulation of active nanomaterials. This work successfully prepares a highly concentrated two dimensional (2D) crystal ink comprised of ultrathin nickel hydroxide (Ni(OH)2) nanosheets with an average lateral size of 34 nm. The maximum concentration of Ni(OH)2 nanosheets in water without adding any additives reaches as high as 50 mg mL−1, which can be printed on arbitrary substrates to form Ni(OH)2 thin films. As a proof-of-concept application, Ni(OH)2 nanosheet ink is coated on commercialized carbon fiber yarns to fabricate wearable energy storage devices. The thus-fabricated hybrid supercapacitors exhibit excellent flexibility with a capacitance retention of 96% after 5000 bending–unbending cycles, and good weavability with a high volumetric capacitance of 36.3 F cm−3 at a current density of 0.4 A cm−3, and an energy density of 11.3 mWh cm−3 at a power density of 0.3 W cm−3. As a demonstration of practical application, a red light emitting diode can be lighted up by three hybrid devices connected in series.A highly concentrated 2D crystal ink comprised of ultrathin Ni(OH)2 nanosheets with an average lateral size of 34 nm is prepared. The Ni(OH)2 nanosheet ink can be printed on commercialized carbon fiber yarn for wearable energy storage devices. The thus-fabricated hybrid supercapacitors exhibit good flexibility and weavability with much improved capacitance and energy density.
      PubDate: 2017-09-01T01:02:02.843414-05:
      DOI: 10.1002/adma.201703455
       
  • Twinned Growth of Metal-Free, Triazine-Based Photocatalyst Films as
           Mixed-Dimensional (2D/3D) van der Waals Heterostructures
    • Authors: Dana Schwarz; Yu Noda, Jan Klouda, Karolina Schwarzová-Pecková, Ján Tarábek, Jiří Rybáček, Jiří Janoušek, Frank Simon, Maksym V. Opanasenko, Jiří Čejka, Amitava Acharjya, Johannes Schmidt, Sören Selve, Valentin Reiter-Scherer, Nikolai Severin, Jürgen P. Rabe, Petra Ecorchard, Junjie He, Miroslav Polozij, Petr Nachtigall, Michael J. Bojdys
      Abstract: Design and synthesis of ordered, metal-free layered materials is intrinsically difficult due to the limitations of vapor deposition processes that are used in their making. Mixed-dimensional (2D/3D) metal-free van der Waals (vdW) heterostructures based on triazine (C3N3) linkers grow as large area, transparent yellow-orange membranes on copper surfaces from solution. The membranes have an indirect band gap (Eg,opt = 1.91 eV, Eg,elec = 1.84 eV) and are moderately porous (124 m2 g−1). The material consists of a crystalline 2D phase that is fully sp2 hybridized and provides structural stability, and an amorphous, porous phase with mixed sp2–sp hybridization. Interestingly, this 2D/3D vdW heterostructure grows in a twinned mechanism from a one-pot reaction mixture: unprecedented for metal-free frameworks and a direct consequence of on-catalyst synthesis. Thanks to the efficient type I heterojunction, electron transfer processes are fundamentally improved and hence, the material is capable of metal-free, light-induced hydrogen evolution from water without the need for a noble metal cocatalyst (34 µmol h−1 g−1 without Pt). The results highlight that twinned growth mechanisms are observed in the realm of “wet” chemistry, and that they can be used to fabricate otherwise challenging 2D/3D vdW heterostructures with composite properties.Mixed-dimensional (2D/3D) layered, van der Waals heterostructures based on triazine linkers are produced in a facile, one-pot, “wet” chemistry process. Macroscopic films of the material grow via a twinned mechanism—first the 2D crystalline phase then the 3D polymer—on a copper support that acts both as a catalyst and template and form an efficient type I heterojunction.
      PubDate: 2017-08-31T11:11:55.887538-05:
      DOI: 10.1002/adma.201703399
       
  • Side Chain Engineering on Medium Bandgap Copolymers to Suppress Triplet
           Formation for High-Efficiency Polymer Solar Cells
    • Authors: Lingwei Xue; Yankang Yang, Jianqiu Xu, Chunfeng Zhang, Haijun Bin, Zhi-Guo Zhang, Beibei Qiu, Xiaojun Li, Chenkai Sun, Liang Gao, Jia Yao, Xiaofeng Chen, Yunxu Yang, Min Xiao, Yongfang Li
      Abstract: Suppression of carrier recombination is critically important in realizing high-efficiency polymer solar cells. Herein, it is demonstrated difluoro-substitution of thiophene conjugated side chain on donor polymer can suppress triplet formation for reducing carrier recombination. A new medium bandgap 2D-conjugated D–A copolymer J91 is designed and synthesized with bi(alkyl-difluorothienyl)-benzodithiophene as donor unit and fluorobenzotriazole as acceptor unit, for taking the advantages of the synergistic fluorination on the backbone and thiophene side chain. J91 demonstrates enhanced absorption, low-lying highest occupied molecular orbital energy level, and higher hole mobility, in comparison with its control polymer J52 without fluorination on the thiophene side chains. The transient absorption spectra indicate that J91 can suppress the triplet formation in its blend film with n-type organic semiconductor acceptor m-ITIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(3-hexylphenyl)-dithieno[2,3-d:2,3′-d′]-s-indaceno[1,2-b:5,6-b′]-dithiophene). With these favorable properties, a higher power conversion efficiency of 11.63% with high VOC of 0.984 V and high JSC of 18.03 mA cm−2 is obtained for the polymer solar cells based on J91/m-ITIC with thermal annealing. The improved photovoltaic performance by thermal annealing is explained from the morphology change upon thermal annealing as revealed by photoinduced force microscopy. The results indicate that side chain engineering can provide a new solution to suppress carrier recombination toward high efficiency, thus deserves further attention.Suppression of carrier recombination is critically important for efficient polymer solar cells. Herein, it is demonstrated that difluoro-substitution of thiophene conjugated side chains on the medium bandgap polymer donor can suppress triplet formation for reducing carrier recombination and improving photovoltaic performance.
      PubDate: 2017-08-31T11:11:17.72229-05:0
      DOI: 10.1002/adma.201703344
       
  • Robust Fe3Mo3C Supported IrMn Clusters as Highly Efficient Bifunctional
           Air Electrode for Metal–Air Battery
    • Authors: Zhiming Cui; Yutao Li, Gengtao Fu, Xiang Li, John B. Goodenough
      Abstract: Catalysts at the air cathode for oxygen reduction and evolution reactions are central to the stability of rechargeable metal–air batteries, an issue that is gaining increasing interest in recent years. Herein, a highly durable and efficient carbide-based bifunctional catalyst consisting of iron–molybdenum carbide (Fe3Mo3C) and IrMn nanoalloys is demonstratred. This carbide is chemically stable in alkaline media and over the potential range of an air cathode. More importantly, Fe3Mo3C is very active for oxygen reduction reaction (ORR) in alkaline media. Fe3Mo3C supported IrMn as a bifunictional catalysts exhibits superior catalytic performance than the state of the art ORR catalyst (Pt/C) and the oxygen evolution reaction catalyst (Ir/C). IrMn/Fe3Mo3C enables Zn–air batteries to achieve long-term cycling performance over 200 h with high efficiency. The extraordinarily high performance of IrMn/Fe3Mo3C bifunictional catalyst provides a very promising alternative to the conventional Pt/C and Ir/C catalyst for an air cathode in alkaline electrolyte.An efficient and cost-effective IrMn/Fe3Mo3C bifunctional catalyst is demonstrated that enables Zn–air battery to achieve long-term cycling performance over 200 h with high efficiency.
      PubDate: 2017-08-30T03:06:36.161012-05:
      DOI: 10.1002/adma.201702385
       
  • Integration of Graphene, Nano Sulfur, and Conducting Polymer into Compact,
           Flexible Lithium–Sulfur Battery Cathodes with Ultrahigh Volumetric
           Capacity and Superior Cycling Stability for Foldable Devices
    • Authors: Peitao Xiao; Fanxing Bu, Guanhui Yang, Yu Zhang, Yuxi Xu
      Abstract: Lithium–sulfur batteries, as one of the most promising next-generation batteries, attract tremendous attentions due to their high energy density and low cost. However, their practical application is hindered by their short cycling life and low volumetric capacity. Herein, compact, flexible, and free-standing films with a sandwich structure are designed simply by vacuum filtration, in which nanosulfur is homogenously coated by graphene and poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). This unique hierarchical structure not only provides a highly conductive network and intimate contacts between nanosulfur and graphene/PEDOT:PSS for effective charge transportation, but also offers synergistic physical restriction and chemical confinement of dissoluble intermediate lithium polysulfides during electrochemical processes. Therefore, these conductive compact films, used directly as cathodes, show the highest reversible volumetric capacity of 1432 Ah L−1 at 0.1 C and 1038 Ah L−1 at 1 C, and excellent cycling stability with a minimal decay rate of 0.04% per cycle over 500 cycles at 1 C. Meanwhile, remarkable rate performance with a high capacity of 701 mAh g−1 at 4 C is also achieved. Soft-packaged batteries based on this flexible cathode are further fabricated and demonstrate excellent mechanical and electrochemical properties with little capacity decay under folded state, highlighting the practical application of our deliberately designed electrode in a flexible power system.A novel compact and flexible film with sandwich structure integrated with graphene, nanosulfur, and poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) is synthesized simply by vacuum filtration. The free-standing film can be used directly as cathodes for lithium–sulfur coin cell batteries with a highest volumetric capacity and long-term cycling stability, and high-performance soft-packaged batteries.
      PubDate: 2017-08-30T03:06:16.087092-05:
      DOI: 10.1002/adma.201703324
       
  • Highly Efficient, Conventional, Fluorescent Organic Light-Emitting Diodes
           with Extended Lifetime
    • Authors: Hyun-Gu Kim; Kwon-Hyeon Kim, Jang-Joo Kim
      Abstract: Highly efficient, yellow-fluorescent organic light-emitting diodes with a maximum external quantum efficiency exceeding 25.0% and extended lifetime are reported using iridium-complex sensitizers doped in an exciplex host. Energy transfer processes reduce the lifetime of the exciplex and excitons on the Ir complexes and enable an excited state to exist in a conventional fluorescent emitter, thereby increasing device lifetime. The device stability depends on the location of the excited state.Highly efficient, conventional, fluorescent organic light-emitting diodes with a maximum external quantum efficiency exceeding 25.0% are fabricated using iridium (Ir) complex sensitizers doped in an exciplex host. Energy-transfer processes reduce the lifetime of the exciplex and excitons in the Ir complex, and enable an excited state to be formed in a conventional fluorescent emitter, thereby increasing device lifetime.
      PubDate: 2017-08-29T03:16:06.37229-05:0
      DOI: 10.1002/adma.201702159
       
  • Giant Incident Photon-to-Current Conversion with Photoconductivity Gain on
           Nanostructured Bismuth Oxysulfide Photoelectrodes under Visible-Light
           Illumination
    • Authors: Evgeny A. Bondarenko; Eugene A. Streltsov, Mikalai V. Malashchonak, Alexander V. Mazanik, Anatoly I. Kulak, Ekaterina V. Skorb
      Abstract: Nanostructured layered bismuth oxysulfide films synthesized by chemical bath deposition reveal a giant incident photon-to-current conversion efficiency (IPCE). This study shows that surprisingly for the cathodic photocurrent in the photoreduction process, the IPCE reaches ≈2500% in aqueous solutions containing [Fe(CN)6]3−. The giant IPCE is observed starting from a certain minimal oxidizer concentration (c> 10−3m for [Fe(CN)6]3−) and decreases nonlinearly with an increase of illumination intensity. Giant IPCE is determined by the decrease in resistivity of the bismuth oxysulfide film under illumination with photoconductivity gain, which provides the possibility of charge carriers from an external circuit to participate in the photoreduction process. Giant IPCE is observed not only in [Fe(CN)6]3− solutions, but also in electrolytes containing other photoelectron acceptors: Fe3+, I3−, quinone, H2O2. In all, solution-processed layered bismuth oxysulfide films offer large-area coverage, nontoxicity, low cost, and compatibility with a wide range of substrates. Abnormally high photoelectrochemical activity, as well as a band gap energy value favorable for efficient conversion of solar light (1.38 eV, direct optical transitions), proves the potential of bismuth oxysulfide photoelectrodes for a new generation of high-performance photoconverters.This study shows a surprisingly giant incident photon-to-current conversion efficiency—about 2500% for the cathodic photocurrent in aqueous solutions containing photoelectron acceptors. Abnormally high photoelectrochemical activity, as well as a band gap energy value favorable for efficient conversion of solar light (1.38 eV, direct optical transitions), proves the potential of bismuth oxysulfide photoelectrodes for a new generation of high-performance photoconverters.
      PubDate: 2017-08-29T03:15:44.629351-05:
      DOI: 10.1002/adma.201702387
       
  • Light-Patterned Crystallographic Direction of a Self-Organized 3D Soft
           Photonic Crystal
    • Authors: Zhi-Gang Zheng; Cong-Long Yuan, Wei Hu, Hari Krishna Bisoyi, Ming-Jie Tang, Zhen Liu, Pei-Zhi Sun, Wei-Qiang Yang, Xiao-Qian Wang, Dong Shen, Yannian Li, Fangfu Ye, Yan-Qing Lu, Guoqiang Li, Quan Li
      Abstract: Uniform and patterned orientation of a crystallographic direction of ordered materials is of fundamental significance and of great interest for electronic and photonic applications. However, such orientation control is generally complicated and challenging with regard to inorganic and organic crystalline materials due to the occurrence of uncontrollable dislocations or defects. Achieving uniform lattice orientation in frustrated liquid-crystalline phases, like cubic blue phases, is a formidable task. Taming and tailoring the ordering of such soft, cubic lattices along predetermined or desired directions, and even imparting a prescribed pattern on lattice orientation, are more challenging, due to the entropy-domination attribute of soft matter. Herein, we disclose a facile way to realize designed micropatterning of a crystallographic direction of a soft, cubic liquid-crystal superstructure, exhibiting an alternate uniform and random orientation of the lattice crystallographic direction enabled by a photoalignment technique. Because of the rewritable trait of the photoalignment film, the pattern can be erased and rewritten on-demand by light. Such an oriented soft lattice sensitively responds to various external stimuli such as temperature, electric field, and light irradiation. Furthermore, advanced reflective photonic applications are achieved based on the patterned crystallographic orientation of the cubic blue phase, soft lattice.A facile way to realize designed micropatterning of a crystallographic direction of a soft, cubic liquid-crystal superstructure is disclosed, exhibiting an alternate uniform and random orientation of the lattice crystallographic direction, enabled by a photoalignment technique, which has not been accomplished before.
      PubDate: 2017-08-28T12:42:15.420613-05:
      DOI: 10.1002/adma.201703165
       
  • Graded Heterojunction Engineering for Hole-Conductor-Free Perovskite Solar
           Cells with High Hole Extraction Efficiency and Conductivity
    • Authors: Bo Li; Yanan Zhang, Luyuan Zhang, Longwei Yin
      Abstract: Despite great progress in the photovoltaic conversion efficiency (PCE) of inorganic–organic hybrid perovskite solar cells (PSCs), the large-scale application of PSCs still faces serious challenges due to the poor-stability and high-cost of the spiro-OMeTAD hole transport layer (HTL). It is of great fundamental importance to rationally address the issues of hole extraction and transfer arising from HTL-free PSCs. Herein, a brand-new PSC architecture is designed by introducing multigraded-heterojunction (GHJ) inorganic perovskite CsPbBrxI3−x layers as an efficient HTL. The grade adjustment can be achieved by precisely tuning the halide proportion and distribution in the CsPbBrxI3−x film to reach an optimal energy alignment of the valance and conduction band between MAPbI3 and CsPbBrxI3−x. The CsPbBrxI3−x GHJ as an efficient HTL can induce an electric field where a valance/conduction band edge is leveraged to bend at the heterojunction interface, boosting the interfacial electron–hole splitting and photoelectron extraction. The GHJ architecture enhances the hole extraction and conduction efficiency from the MAPbI3 to the counter electrode, decreases the recombination loss during the hole transfer, and benefits in increasing the open-circuit voltage. The optimized HTL-free PCS based on the GHJ architecture demonstrates an outstanding thermal stability and a significantly improved PCE of 11.33%, nearly 40% increase compared with 8.16% for pure HTL-free devices.Through energy-band engineering, a brand-new perovskite solar cell architecture with multigraded-heterojunction (GHJ) inorganic perovskite CsPbBrxI3−x layers as an efficient hole transport layer is designed. The GHJ architecture enhances the hole extraction and conduction efficiency, and decreases the recombination loss during the hole transfer. A certified efficiency of 11.33% is obtained and the high-performing devices show outstanding thermal- and humidity-stability.
      PubDate: 2017-08-28T12:41:41.398353-05:
      DOI: 10.1002/adma.201701221
       
  • Locking and Unlocking the Molecular Spin Crossover Transition
    • Authors: Xin Zhang; Paulo S. Costa, James Hooper, Daniel P. Miller, Alpha T. N'Diaye, Sumit Beniwal, Xuanyuan Jiang, Yuewei Yin, Patrick Rosa, Lucie Routaboul, Mathieu Gonidec, Lorenzo Poggini, Pierre Braunstein, Bernard Doudin, Xiaoshan Xu, Axel Enders, Eva Zurek, Peter A. Dowben
      Abstract: The Fe(II) spin crossover complex [Fe{H2B(pz)2}2(bipy)] (pz = pyrazol-1-yl, bipy = 2,2′-bipyridine) can be locked in a largely low-spin-state configuration over a temperature range that includes temperatures well above the thermal spin crossover temperature of 160 K. This locking of the spin state is achieved for nanometer thin films of this complex in two distinct ways: through substrate interactions with dielectric substrates such as SiO2 and Al2O3, or in powder samples by mixing with the strongly dipolar zwitterionic p-benzoquinonemonoimine C6H2(—⋯ NH2)2(—⋯ O)2. Remarkably, it is found in both cases that incident X-ray fluences then restore the [Fe{H2B(pz)2}2(bipy)] moiety to an electronic state characteristic of the high spin state at temperatures of 200 K to above room temperature; that is, well above the spin crossover transition temperature for the pristine powder, and well above the temperatures characteristic of light- or X-ray-induced excited-spin-state trapping. Heating slightly above room temperature allows the initial locked state to be restored. These findings, supported by theory, show how the spin crossover transition can be manipulated reversibly around room temperature by appropriate design of the electrostatic and chemical environment.Locking of the spin state of a molecular spin crossover system has been achieved, and room-temperature optical isothermal switching from a low spin to high spin state is demonstrated. Key ingredients necessary for a room temperature molecular magnetoelectric are now realizable.
      PubDate: 2017-08-28T12:41:15.857197-05:
      DOI: 10.1002/adma.201702257
       
  • Thiol–Ene Click Reaction as a Facile and General Approach for Surface
           Functionalization of Colloidal Nanocrystals
    • Authors: Bin Liu; Xiaoran Deng, Zhongxi Xie, Ziyong Cheng, Piaoping Yang, Jun Lin
      Abstract: Oleic acid (OA) and/or oleylamine (OAm) are generally used as the surface ligands for stabilization of inorganic nanocrystals (NCs). The hydrophobic and inert surface of the NCs limits their applications such as in biomedical areas. Hence, surface modifications are essential in many physical and chemical processes. Here, a facile and versatile strategy is reported for the modification of NCs by ultraviolet-induced thiol–ene chemistry, in which thiol-terminated poly(ethylene glycol) (HSPEG) and its derivatives can react directly with double bonds in OA/OAm ligands to form covalent linking within one step. Through this strategy, various hydrophobic NCs with different compositions and morphologies are able to be transferred into water combining with functionalization of active groups. As a proof-of-concept, this strategy is successfully used to construct a sensor for detecting avidin based on upconverting luminescence analysis. Therefore, this strategy provides a new tool for designing and tuning the surface properties of NCs for different applications.The modification of nanocrystals (NCs) by ultraviolet-induced thiol–ene chemistry through a facile and versatile strategy is reported, in which thiol-terminated poly(ethylene glycol) (HSPEG) and its derivatives can react directly with double bonds in oleic acid/oleylamine ligands to form covalent linking within one step. This strategy provides a new tool for designing and tuning the surface properties of NCs.
      PubDate: 2017-08-10T01:20:59.556453-05:
      DOI: 10.1002/adma.201604878
       
  • A Novel Phase-Transformation Activation Process toward Ni–Mn–O
           Nanoprism Arrays for 2.4 V Ultrahigh-Voltage Aqueous Supercapacitors
    • Authors: Wenhua Zuo; Chaoyue Xie, Pan Xu, Yuanyuan Li, Jinping Liu
      Abstract: One of the key challenges of aqueous supercapacitors is the relatively low voltage (0.8–2.0 V), which significantly limits the energy density and feasibility of practical applications of the device. Herein, this study reports a novel Ni–Mn–O solid-solution cathode to widen the supercapacitor device voltage, which can potentially suppress the oxygen evolution reaction and thus be operated stably within a quite wide potential window of 0–1.4 V (vs saturated calomel electrode) after a simple but unique phase-transformation electrochemical activation. The solid-solution structure is designed with an ordered array architecture and in situ nanocarbon modification to promote the charge/mass transfer kinetics. By paring with commercial activated carbon anode, an ultrahigh voltage asymmetric supercapacitor in neutral aqueous LiCl electrolyte is assembled (2.4 V; among the highest for single-cell supercapacitors). Moreover, by using a polyvinyl alcohol (PVA)–LiCl electrolyte, a 2.4 V hydrogel supercapacitor is further developed with an excellent Coulombic efficiency, good rate capability, and remarkable cycle life (>5000 cycles; 95.5% capacity retention). Only one cell can power the light-emitting diode indicator brightly. The resulting maximum volumetric energy density is 4.72 mWh cm−3, which is much superior to previous thin-film manganese-oxide-based supercapacitors and even battery–supercapacitor hybrid devices.A very simple but unique phase-transformation electrochemical activation strategy is developed to enable a solid-solution Ni–Mn–O nanoprism array to suppress the oxygen evolution and exhibit ultrawide stable electrochemical window (0–1.4 V vs saturated calomel electrode). With such as an array as the cathode, a 2.4 V ultrahigh voltage aqueous supercapacitor is constructed, demonstrating high volumetric energy/power densities.
      PubDate: 2017-08-07T07:37:21.674303-05:
      DOI: 10.1002/adma.201703463
       
  • An “On-Site Transformation” Strategy for Treatment of
           Bacterial Infection
    • Authors: Guo-Bin Qi; Di Zhang, Fu-Hua Liu, Zeng-Ying Qiao, Hao Wang
      Abstract: To date, numerous nanosystems have been developed as antibiotic replacements for bacterial infection treatment. However, these advanced systems are limited owing to their nontargeting accumulation and the consequent side effects. Herein, transformable polymer–peptide biomaterials have been developed that enable specific accumulation in the infectious site and long-term retention, resulting in enhanced binding capability and killing efficacy toward bacteria. The polymer–peptide conjugates are composed of a chitosan backbone and two functional peptides, i.e., an antimicrobial peptide and a poly(ethylene glycol)-tethered enzyme-cleavable peptide (CPC-1). The CPC-1 initially self-assembles into nanoparticles with pegylated coronas. Upon the peptides are cleaved by the gelatinase secreted by a broad spectrum of bacterial species, the resultant compartments of nanoparticles spontaneously transformed into fibrous nanostructures that are stabilized by enhanced chain–chain interaction, leading to exposure of antimicrobial peptide residues for multivalent cooperative electrostatic interactions with bacterial membranes. Intriguingly, the in situ morphological transformation also critically improves the accumulation and retention of CPC-1 in infectious sites in vivo, which exhibits highly efficient antibacterial activity. This proof-of-concept study demonstrates that pathological environment-driven smart self-assemblies may provide a new idea for design of high-performance biomaterials for disease diagnostics and therapeutics.Transformable chitosan–peptide biomaterials (CPC-1) initially self-assemble into nanoparticles with PEGylated coronas. Upon cleavage of the peptides by gelatinase, the resultant compartments of the nanoparticles spontaneously transform into fibrous nanostructures. The in situ morphological transformation critically improves the accumulation and retention of CPC-1 in infectious sites in vivo, which exhibits highly efficient antibacterial activity.
      PubDate: 2017-08-07T07:16:19.130593-05:
      DOI: 10.1002/adma.201703461
       
  • Tiered Electron Anions in Multiple Voids of LaScSi and Their Applications
           to Ammonia Synthesis
    • Authors: Jiazhen Wu; Yutong Gong, Takeshi Inoshita, Daniel C. Fredrickson, Junjie Wang, Yangfan Lu, Masaaki Kitano, Hideo Hosono
      Abstract: Electrides—compounds in which electrons localized in interstitial spaces periodically serve as anions—have attracted broad attention for their exotic properties, such as extraordinary electron-donating ability. In our efforts to expand this small family of phases, LaScSi emerges as a promising candidate. Its electron count is 2e− f.u.−1 in excess of that expected from the Zintl concept, while its structure offers interstitial spaces that can accommodate these extra electrons. Herein, this potential is explored through density functional theory (DFT) calculations and property measurements on LaScSi. DFT calculations (validated by heat capacity and electrical transport measurements) reveal electron density peaks at two symmetry-distinct interstitial sites. Importantly, this electride-like character is combined with chemical stability in air and water, an advantage for catalysis. Ru-loaded LaScSi shows outstanding catalytic activity for ammonia synthesis, with a turnover frequency (0.1 s−1 at 0.1 MPa, 400 °C) an order of magnitude higher than those of oxide-based Ru catalysts, e.g., Ru/MgO. As with other electrides, LaScSi's ability to reversibly store hydrogen prevents the hydrogen poisoning of Ru surfaces. The better performance of LaScSi, however, hints at the importance of the high concentration (>1.6 × 1022 cm−3) and tiered nature of its anionic electrons, which offers guidance toward new catalysts.A new electride candidate, LaScSi, which contains two types of interstitial voids accommodating symmetry-distinct electron anions, is presented. The unique structural, electronic, and chemical properties endow Ru/LaScSi with outstanding catalytic activity for ammonia synthesis, as indicated by the turnover frequency of 0.1 s−1, which is one order of magnitude higher than those of oxide-based Ru catalysts.
      PubDate: 2017-07-31T06:13:48.843237-05:
      DOI: 10.1002/adma.201700924
       
  • Amino-Mediated Anchoring Perovskite Quantum Dots for Stable and
           Low-Threshold Random Lasing
    • Authors: Xiaoming Li; Yue Wang, Handong Sun, Haibo Zeng
      Abstract: Halide perovskite quantum dots (Pe-QDs) have been considered as outstanding candidates for photodetector, light-emitting diode, and lasing applications, but these perspectives are being impeded by the severe stability, including both chemical and optical degradations. This study reports on amino-mediated anchoring Pe-QDs onto the surfaces of monodisperse silica to effectively depress the optical degradation of their photoluminescence (PL) and random lasing stabilities, hence achieving highly stable and low-threshold lasing. An amination-mediated nucleation and growth process is designed for the general and one-pot synthesis of Pe-QDs on the surfaces of silica spheres. The facile synthetic process, which can be finished within several minutes, insures scalable production. Surprisingly, almost no PL degradation is observed after 40 d storage under ambient conditions, even 80% PL intensity can be maintained after persistently illuminated by UV lamps for 108 h. Subsequently, extremely stable random lasing is achieved after storage for 2 months or over continuously optical pumping for 8 h. Such high PL and lasing stabilities originate from the isolation effects due to the effective anchoring, which separate the Pe-QDs from each other and inhibit the photoinduced regrowth and deterioration. This work will also open the window of perovskite-based multifunctional systems.Amino-mediated anchoring of perovskite quantum dots (QDs) onto the surfaces of monodisperse silica spheres separates the QDs from each other and inhibits the photoinduced regrowth and deterioration effectively, which also contributes to highly stable and low-threshold random lasing. The general and one-pot synthetic procedures ensure scalable production and open the window of perovskite-based multifunctional systems.
      PubDate: 2017-07-31T06:11:10.859803-05:
      DOI: 10.1002/adma.201701185
       
  • Supercapacitive Iontronic Nanofabric Sensing
    • Authors: Ruya Li; Yang Si, Zijie Zhu, Yaojun Guo, Yingjie Zhang, Ning Pan, Gang Sun, Tingrui Pan
      Abstract: The study of wearable devices has become a popular research topic recently, where high-sensitivity, noise proof sensing mechanisms with long-term wearability play critical roles in a real-world implementation, while the existing mechanical sensing technologies (i.e., resistive, capacitive, or piezoelectric) have yet offered a satisfactory solution to address them all. Here, we successfully introduced a flexible supercapacitive sensing modality to all-fabric materials for wearable pressure and force sensing using an elastic ionic–electronic interface. Notably, an electrospun ionic fabric utilizing nanofibrous structures offers an extraordinarily high pressure-to-capacitance sensitivity (114 nF kPa−1), which is at least 1000 times higher than any existing capacitive sensors and one order of magnitude higher than the previously reported ionic devices, with a pressure resolution of 2.4 Pa, achieving high levels of noise immunity and signal stability for wearable applications. In addition, its fabrication process is fully compatible with existing industrial manufacturing and can lead to cost-effective production for its utility in emerging wearable uses in a foreseeable future.A flexible supercapacitive sensing modality to all-fabric materials is introduced for wearable pressure and force sensing using an elastic ionic–electronic interface. Utilizing an electrospun iontronic nanofabric as the sensing element, the all-fabric supercapacitive iontronic device offers an unprecedented sensitivity (114 nF kPa−1), 2.4 Pa pressure resolution, and milliseconds response time, achieving high levels of noise immunity and signal stability for wearable applications.
      PubDate: 2017-07-31T02:22:14.48312-05:0
      DOI: 10.1002/adma.201700253
       
  • Exceptional High-Performance of Pt-Based Bimetallic Catalysts for
           Exclusive Detection of Exhaled Biomarkers
    • Authors: Sang-Joon Kim; Seon-Jin Choi, Ji-Soo Jang, Hee-Jin Cho, Won-Tae Koo, Harry L. Tuller, Il-Doo Kim
      Abstract: Achieving an improved understanding of catalyst properties, with ability to predict new catalytic materials, is key to overcoming the inherent limitations of metal oxide based gas sensors associated with rather low sensitivity and selectivity, particularly under highly humid conditions. This study introduces newly designed bimetallic nanoparticles (NPs) employing bimetallic Pt-based NPs (PtM, where M = Pd, Rh, and Ni) via a protein encapsulating route supported on mesoporous WO3 nanofibers. These structures demonstrate unprecedented sensing performance for detecting target biomarkers (even at p.p.b. levels) in highly humid exhaled breath. Sensor arrays are further employed to enable pattern recognition capable of discriminating between simulated biomarkers and controlled breath. The results provide a new class of multicomponent catalytic materials, demonstrating potential for achieving reliable breath analysis sensing.Effective strategy to readily synthesize highly dispersed Pt-based bimetallic (PtM, where M = Pd, Rh, and Ni) NPs as a new class of active catalysts is successfully developed on the highly porous architecture of 1D WO3 nanofibers via a protein template, i.e., apoferritin, in combination with the electrospinning method for superior exhaled-breath sensors.
      PubDate: 2017-07-31T01:36:10.355709-05:
      DOI: 10.1002/adma.201700737
       
  • A Hollow-Structured CuS@Cu2S@Au Nanohybrid: Synergistically Enhanced
           Photothermal Efficiency and Photoswitchable Targeting Effect for Cancer
           Theranostics
    • Authors: Xiaoran Deng; Kai Li, Xuechao Cai, Bin Liu, Yi Wei, Kerong Deng, Zhongxi Xie, Zhijian Wu, Ping'an Ma, Zhiyao Hou, Ziyong Cheng, Jun Lin
      Abstract: It is of great importance in drug delivery to fabricate multifunctional nanocarriers with intelligent targeting properties, for cancer diagnosis and therapy. Herein, hollow-structured CuS@Cu2S@Au nanoshell/satellite nanoparticles are designed and synthesized for enhanced photothermal therapy and photoswitchable targeting theranostics. The remarkably improved photothermal conversion efficiency of CuS@Cu2S@Au under 808 nm near-infrared (NIR) laser irradiation can be explained by the reduced bandgap and more circuit paths for electron transitions for CuS and Cu2S modified with Au nanoparticles, as calculated by the Vienna ab initio simulation package, based on density functional theory. By modification of thermal-isomerization RGD targeting molecules and thermally sensitive copolymer on the surface of nanoparticles, the transition of the shielded/unshielded mode of RGD (Arg-Gly-Asp) targeting molecules and shrinking of the thermally sensitive polymer by NIR photoactivation can realize a photoswitchable targeting effect. After loading an anticancer drug doxorubicin in the cavity of CuS@Cu2S@Au, the antitumor therapy efficacy is greatly enhanced by combining chemo- and photothermal therapy. The reported nanohybrid can also act as a photoacoustic imaging agent and an NIR thermal imaging agent for real-time imaging, which provides a versatile platform for multifunctional theranostics and stimuli-responsive targeted cancer therapy.A novel hollow CuS@Cu2S@Au nanoshell/satellite structure is presented that can synergistically enhance photothermal therapy under 808 nm near-infrared irradiation and cooperative molecular conformation motion for photoswitchable targeting to U87MG cancer cells.
      PubDate: 2017-07-26T07:21:30.832779-05:
      DOI: 10.1002/adma.201701266
       
  • Highly Luminescent 2D-Type Slab Crystals Based on a Molecular
           Charge-Transfer Complex as Promising Organic Light-Emitting Transistor
           Materials
    • Authors: Sang Kyu Park; Jin Hong Kim, Tatsuhiko Ohto, Ryo Yamada, Andrew O. F. Jones, Dong Ryeol Whang, Illhun Cho, Sangyoon Oh, Seung Hwa Hong, Ji Eon Kwon, Jong H. Kim, Yoann Olivier, Roland Fischer, Roland Resel, Johannes Gierschner, Hirokazu Tada, Soo Young Park
      Abstract: A new 2:1 donor (D):acceptor (A) mixed-stacked charge-transfer (CT) cocrystal comprising isometrically structured dicyanodistyrylbenzene-based D and A molecules is designed and synthesized. Uniform 2D-type morphology is manifested by the exquisite interplay of intermolecular interactions. In addition to its appealing structural features, unique optoelectronic properties are unveiled. Exceptionally high photoluminescence quantum yield (ΦF ≈ 60%) is realized by non-negligible oscillator strength of the S1 transition, and rigidified 2D-type structure. Moreover, this luminescent 2D-type CT crystal exhibits balanced ambipolar transport (µh and µe of ≈10−4 cm2 V−1 s−1). As a consequence of such unique optoelectronic characteristics, the first CT electroluminescence is demonstrated in a single active-layered organic light-emitting transistor (OLET) device. The external quantum efficiency of this OLET is as high as 1.5% to suggest a promising potential of luminescent mixed-stacked CT cocrystals in OLET applications.A novel 2D-type slab crystal based on 2:1 donor:acceptor mixed-stacked charge-transfer (CT) complex is developed. Unique optoelectronic properties: balanced ambipolar transport (µe, µh ≈ 10−4 cm2 V−1 s−1) and bright luminescence (ΦF ≈ 60%) are successfully bridged in organic field-effect transistor (OFET) devices, demonstrating the first CT organic light-emitting transistors with high external quantum efficiency up to 1.5%.
      PubDate: 2017-07-26T07:20:59.99255-05:0
      DOI: 10.1002/adma.201701346
       
  • Edge Sites with Unsaturated Coordination on Core–Shell
           Mn3O4@MnxCo3−xO4 Nanostructures for Electrocatalytic Water Oxidation
    • Authors: Congling Hu; Lei Zhang, Zhi-Jian Zhao, Jun Luo, Jing Shi, Zhiqi Huang, Jinlong Gong
      Abstract: Transition-metal oxides are extensively investigated as efficient electrocatalysts for the oxygen evolution reaction (OER). However, large-scale applications remain challenging due to their moderate catalytic activity. Optimized regulation of surface states can lead to improvement of catalytic properties. Here, the design of Mn@CoxMn3−xO4 nanoparticles with abundant edge sites via a simple seed-mediated growth strategy is described. The unsaturated coordination generated on the edge sites of CoxMn3−xO4 shells makes a positive contribution to the surface-structure tailoring. Density functional theory calculations indicate that the edge sites with unsaturated coordination exhibit intense affinity for OH− in the alkaline electrolyte, which greatly enhances the electrochemical OER performance of the catalysts. The resulting Mn@CoxMn3−xO4 catalysts yield a current density of 10 mA cm−2 at an overpotential of 246 mV and a relatively low Tafel slope of 46 mV dec−1. The successful synthesis of these metal oxides nanoparticles with edge sites may pave a new path for rationally fabricating efficient OER catalysts.Mn@CoxMn3−xO4 nanoparticles with abundant edge sites are designed and synthesized via a simple seed-mediated growth strategy. The edge sites with unsaturated coordination exhibit intense affinity for OH− in the alkaline electrolyte, which greatly enhances the electrochemical oxygen evolution reaction performance.
      PubDate: 2017-07-26T07:16:12.856453-05:
      DOI: 10.1002/adma.201701820
       
  • A Strategy to Produce High Efficiency, High Stability Perovskite Solar
           Cells Using Functionalized Ionic Liquid-Dopants
    • Authors: Yi Zhang; Zhaofu Fei, Peng Gao, Yonghui Lee, Farzaneh Fadaei Tirani, Rosario Scopelliti, Yaqing Feng, Paul J. Dyson, Mohammad Khaja Nazeeruddin
      Abstract: Functionalized imidazolium iodide salts (ionic liquids) modified with CH2CHCH2, CH2CCH, or CH2CN groups are applied as dopants in the synthesis of CH3NH3PbI3-type perovskites together with a fumigation step. Notably, a solar cell device prepared from the perovskite film doped with the salt containing the CH2CHCH2 side-chain has a power conversion efficiency of 19.21%, which is the highest efficiency reported for perovskite solar cells involving a fumigation step. However, doping with the imidazolium salts with the CH2CCH and CH2CN groups result in perovskite layers that lead to solar cell devices with similar or lower power conversion efficiencies than the dopant-free cell.Perovskite films, grown from PbI2:MAI in DMSO in the presence of functionalized ionic-liquid (imidazolium iodide) dopants and incorporated into perovskite solar cells, are reported. One cell has a power conversion efficiency exceeding 19%. Difference in power conversion efficiency can be traced to the physical properties of imidazolium-PbI3 salts that form during the preparation of the film.
      PubDate: 2017-07-25T06:21:45.027843-05:
      DOI: 10.1002/adma.201702157
       
  • Transparent, Flexible, and Conductive 2D Titanium Carbide (MXene) Films
           with High Volumetric Capacitance
    • Authors: Chuanfang (John) Zhang; Babak Anasori, Andrés Seral-Ascaso, Sang-Hoon Park, Niall McEvoy, Aleksey Shmeliov, Georg S. Duesberg, Jonathan N. Coleman, Yury Gogotsi, Valeria Nicolosi
      Abstract: 2D transition-metal carbides and nitrides, known as MXenes, have displayed promising properties in numerous applications, such as energy storage, electromagnetic interference shielding, and catalysis. Titanium carbide MXene (Ti3C2Tx), in particular, has shown significant energy-storage capability. However, previously, only micrometer-thick, nontransparent films were studied. Here, highly transparent and conductive Ti3C2Tx films and their application as transparent, solid-state supercapacitors are reported. Transparent films are fabricated via spin-casting of Ti3C2Tx nanosheet colloidal solutions, followed by vacuum annealing at 200 °C. Films with transmittance of 93% (≈4 nm) and 29% (≈88 nm) demonstrate DC conductivity of ≈5736 and ≈9880 S cm−1, respectively. Such highly transparent, conductive Ti3C2Tx films display impressive volumetric capacitance (676 F cm−3) combined with fast response. Transparent solid-state, asymmetric supercapacitors (72% transmittance) based on Ti3C2Tx and single-walled carbon nanotube (SWCNT) films are also fabricated. These electrodes exhibit high capacitance (1.6 mF cm−2) and energy density (0.05 µW h cm−2), and long lifetime (no capacitance decay over 20 000 cycles), exceeding that of graphene or SWCNT-based transparent supercapacitor devices. Collectively, the Ti3C2Tx films are among the state-of-the-art for future transparent, conductive, capacitive electrodes, and translate into technologically viable devices for next-generation wearable, portable electronics.Highly transparent and conductive Ti3C2Tx films and their application as transparent, solid-state supercapacitors are demonstrated. Films with transmittance of 93% (≈4 nm) and 29% (≈88 nm) demonstrate DC conductivity of ≈5736 and ≈9880 S cm−1, respectively. The Ti3C2Tx films display impressive volumetric capacitance (676 F cm−3), high areal capacitance, and long lifetime in the transparent solid-state supercapacitor devices.
      PubDate: 2017-07-25T01:26:54.994657-05:
      DOI: 10.1002/adma.201702678
       
  • Protected Lithium-Metal Anodes in Batteries: From Liquid to Solid
    • Authors: Chunpeng Yang; Kun Fu, Ying Zhang, Emily Hitz, Liangbing Hu
      Abstract: High-energy lithium-metal batteries are among the most promising candidates for next-generation energy storage systems. With a high specific capacity and a low reduction potential, the Li-metal anode has attracted extensive interest for decades. Dendritic Li formation, uncontrolled interfacial reactions, and huge volume effect are major hurdles to the commercial application of Li-metal anodes. Recent studies have shown that the performance and safety of Li-metal anodes can be significantly improved via organic electrolyte modification, Li-metal interface protection, Li-electrode framework design, separator coating, and so on. Superior to the liquid electrolytes, solid-state electrolytes are considered able to inhibit problematic Li dendrites and build safe solid Li-metal batteries. Inspired by the bright prospects of solid Li-metal batteries, increasing efforts have been devoted to overcoming the obstacles of solid Li-metal batteries, such as low ionic conductivity of the electrolyte and Li–electrolyte interfacial problems. Here, the approaches to protect Li-metal anodes from liquid batteries to solid-state batteries are outlined and analyzed in detail. Perspectives regarding the strategies for developing Li-metal anodes are discussed to facilitate the practical application of Li-metal batteries.Lithium-metal batteries are promising candidates for high-energy and cost-effective energy-storage systems. Solving the dendritic problem and interfacial instability of the Li-metal anodes is a prerequisite to their practical utilization. Strategies to protect Li-metal anodes in liquid and solid-state electrolytes, which will facilitate the development safe and high-performance Li-metal batteries, are reviewed.
      PubDate: 2017-07-24T15:25:17.783351-05:
      DOI: 10.1002/adma.201701169
       
  • Vacancy-Driven Gelation Using Defect-Rich Nanoassemblies of 2D Transition
           Metal Dichalcogenides and Polymeric Binder for Biomedical Applications
    • Authors: Manish K. Jaiswal; James K. Carrow, James L. Gentry, Jagriti Gupta, Nara Altangerel, Marlan Scully, Akhilesh K. Gaharwar
      Abstract: A new approach of vacancy-driven gelation to obtain chemically crosslinked hydrogels from defect-rich 2D molybdenum disulfide (MoS2) nanoassemblies and polymeric binder is reported. This approach utilizes the planar and edge atomic defects available on the surface of the 2D MoS2 nanoassemblies to form mechanically resilient and elastomeric nanocomposite hydrogels. The atomic defects present on the lattice plane of 2D MoS2 nanoassemblies are due to atomic vacancies and can act as an active center for vacancy-driven gelation with a thiol-activated terminal such as four-arm poly(ethylene glycol)–thiol (PEG-SH) via chemisorption. By modulating the number of vacancies on the 2D MoS2 nanoassemblies, the physical and chemical properties of the hydrogel network can be controlled. This vacancy-driven gelation process does not require external stimuli such as UV exposure, chemical initiator, or thermal agitation for crosslinking and thus provides a nontoxic and facile approach to encapsulate cells and proteins. 2D MoS2 nanoassemblies are cytocompatible, and encapsulated cells in the nanocomposite hydrogels show high viability. Overall, the nanoengineered hydrogel obtained from vacancy-driven gelation is mechanically resilient and can be used for a range of biomedical applications including tissue engineering, regenerative medicine, and cell and therapeutic delivery.A new approach of vacancy-driven gelation to obtain chemically crosslinked hydrogels from defect-rich nanoassemblies of 2D transition metal dichalcogenides and polymeric binder is presented. The approach utilizes planar and edge atomic defects available on the surface of 2D MoS2 to form a chemically reinforced mechanically resilient nanocomposite network. Mechanically stiff and elastomeric nanocomposites hydrogels can be used to encapsulate cells for biomedical applications.
      PubDate: 2017-07-24T15:22:06.619175-05:
      DOI: 10.1002/adma.201702037
       
  • Direct Observation of Inherent Atomic-Scale Defect Disorders responsible
           for High-Performance Ti1−xHfxNiSn1−ySby Half-Heusler Thermoelectric
           Alloys
    • Authors: Ki Sung Kim; Young-Min Kim, Hyeona Mun, Jisoo Kim, Jucheol Park, Albina Y. Borisevich, Kyu Hyoung Lee, Sung Wng Kim
      Abstract: Structural defects often dominate the electronic- and thermal-transport properties of thermoelectric (TE) materials and are thus a central ingredient for improving their performance. However, understanding the relationship between TE performance and the disordered atomic defects that are generally inherent in nanostructured alloys remains a challenge. Herein, the use of scanning transmission electron microscopy to visualize atomic defects directly is described and disordered atomic-scale defects are demonstrated to be responsible for the enhancement of TE performance in nanostructured Ti1−xHfxNiSn1−ySby half-Heusler alloys. The disordered defects at all atomic sites induce a local composition fluctuation, effectively scattering phonons and improving the power factor. It is observed that the Ni interstitial and Ti,Hf/Sn antisite defects are collectively formed, leading to significant atomic disorder that causes the additional reduction of lattice thermal conductivity. The Ti1−xHfxNiSn1−ySby alloys containing inherent atomic-scale defect disorders are produced in one hour by a newly developed process of temperature-regulated rapid solidification followed by sintering. The collective atomic-scale defect disorder improves the zT to 1.09 ± 0.12 at 800 K for the Ti0.5Hf0.5NiSn0.98Sb0.02 alloy. These results provide a promising avenue for improving the TE performance of state-of-the-art materials.Disordered defects at all atomic sites induce a local composition fluctuation, effectively scattering phonons and improving power factors. Direct observation of atomic-scale defect disorders clarifies an enhancement of thermoelectric performance originating from a significant reduction of thermal conductivity in half-Heulser alloys. The collective atomic-scale defect disorder improves the zT to 1.09 ± 0.12 at 800 K for the Ti0.5Hf0.5NiSn0.98Sb0.02 alloy.
      PubDate: 2017-07-24T07:11:31.116819-05:
      DOI: 10.1002/adma.201702091
       
  • High Efficiency Nonfullerene Polymer Solar Cells with Thick Active Layer
           and Large Area
    • Authors: Bing Guo; Wanbin Li, Xia Guo, Xiangyi Meng, Wei Ma, Maojie Zhang, Yongfang Li
      Abstract: In this work, high-efficiency nonfullerene polymer solar cells (PSCs) are developed based on a thiazolothiazole-containing wide bandgap polymer PTZ1 as donor and a planar IDT-based narrow bandgap small molecule with four side chains (IDIC) as acceptor. Through thermal annealing treatment, a power conversion efficiency (PCE) of up to 11.5% with an open circuit voltage (Voc) of 0.92 V, a short-circuit current density (Jsc) of 16.4 mA cm−2, and a fill factor of 76.2% is achieved. Furthermore, the PSCs based on PTZ1:IDIC still exhibit a relatively high PCE of 9.6% with the active layer thickness of 210 nm and a superior PCE of 10.5% with the device area of up to 0.81 cm2. These results indicate that PTZ1 is a promising polymer donor material for highly efficient fullerene-free PSCs and large-scale devices fabrication.The nonfullerene polymer solar cells based on a wide-bandgap polymer PTZ1 and a narrow-bandgap acceptor IDIC exhibit weak active-layer thickness and area dependence with an optimal power conversion efficiency of 11.5%, indicating that the blend of PTZ1/IDIC has potential for the practical application of polymer solar cells.
      PubDate: 2017-07-24T01:32:37.645834-05:
      DOI: 10.1002/adma.201702291
       
  • Isoindigo-Based Polymers with Small Effective Masses for High-Mobility
           Ambipolar Field-Effect Transistors
    • Authors: Jie Yang; Zhiyuan Zhao, Hua Geng, Changli Cheng, Jinyang Chen, Yunlong Sun, Longxian Shi, Yuanping Yi, Zhigang Shuai, Yunlong Guo, Shuai Wang, Yunqi Liu
      Abstract: So far, most of the reported high-mobility conjugated polymers are p-type semiconductors. By contrast, the advances in high-mobility ambipolar polymers fall greatly behind those of p-type counterparts. Instead of unipolar p-type and n-type materials, ambipolar polymers, especially balanced ambipolar polymers, are potentially serviceable for easy-fabrication and low-cost complementary metal-oxide-semiconductor circuits. Therefore, it is a critical issue to develop high-mobility ambipolar polymers. Here, three isoindigo-based polymers, PIID-2FBT, P1FIID-2FBT, and P2FIID-2FBT are developed for high-performance ambipolar organic field-effect transistors. After the incorporation of fluorine atoms, the polymers exhibit enhanced coplanarity, lower energy levels, higher crystallinity, and thus increased µe. P2FIID-2FBT exhibits n-type dominant performance with a µe of 9.70 cm2 V−1 s−1. Moreover, P1FIID-2FBT exhibits a highly balanced µh and µe of 6.41 and 6.76 cm2 V−1 s−1, respectively, which are among the highest values for balanced ambipolar polymers. Moreover, a concept “effective mass” is introduced to further study the reasons for the high performance of the polymers. All the polymers have small effective masses, indicating good intramolecular charge transport. The results demonstrate that high-mobility ambipolar semiconductors can be obtained by designing polymers with fine-tuned energy levels, small effective masses, and high crystallinity.Three isoindigo-based polymers, PIID-2FBT, P1FIID-2FBT, and P2FIID-2FBT are developed for high-performance ambipolar organic field-effect transistors. After the incorporation of fluorine atoms, the polymers show that an obvious mobility change from p-channel dominant to n-channel dominant transport characteristics. Especially, P1FIID-2FBT exhibits a highly balanced electron/hole mobility, resulting from the fine-tuned energy levels, high crystallinity, and relatively small effective mass.
      PubDate: 2017-07-24T01:31:58.635284-05:
      DOI: 10.1002/adma.201702115
       
  • Nitrogen-Superdoped 3D Graphene Networks for High-Performance
           Supercapacitors
    • Authors: Weili Zhang; Chuan Xu, Chaoqun Ma, Guoxian Li, Yuzuo Wang, Kaiyu Zhang, Feng Li, Chang Liu, Hui-Ming Cheng, Youwei Du, Nujiang Tang, Wencai Ren
      Abstract: An N-superdoped 3D graphene network structure with an N-doping level up to 15.8 at% for high-performance supercapacitor is designed and synthesized, in which the graphene foam with high conductivity acts as skeleton and nested with N-superdoped reduced graphene oxide arogels. This material shows a highly conductive interconnected 3D porous structure (3.33 S cm−1), large surface area (583 m2 g−1), low internal resistance (0.4 Ω), good wettability, and a great number of active sites. Because of the multiple synergistic effects of these features, the supercapacitors based on this material show a remarkably excellent electrochemical behavior with a high specific capacitance (of up to 380, 332, and 245 F g−1 in alkaline, acidic, and neutral electrolytes measured in three-electrode configuration, respectively, 297 F g−1 in alkaline electrolytes measured in two-electrode configuration), good rate capability, excellent cycling stability (93.5% retention after 4600 cycles), and low internal resistance (0.4 Ω), resulting in high power density with proper high energy density.A N-superdoped 3D graphene network structure is synthesized to achieve a highly conductive interconnected 3D porous structure and high N-doping level simultaneously. The supercapacitors based on this material show a remarkably high capacity, good rate capability, and excellent cycling stability.
      PubDate: 2017-07-24T01:31:25.932433-05:
      DOI: 10.1002/adma.201701677
       
  • Extremely Low Density and Super-Compressible Graphene Cellular Materials
    • Authors: Ling Qiu; Bing Huang, Zijun He, Yuanyuan Wang, Zhiming Tian, Jefferson Zhe Liu, Kun Wang, Jingchao Song, Thomas R. Gengenbach, Dan Li
      Abstract: Development of extremely low density graphene elastomer (GE) holds the potential to enable new properties that traditional cellular materials cannot offer, which are promising for a range of emerging applications, ranging from flexible electronics to multifunctional scaffolds. However, existing graphene foams with extremely low density are generally found to have very poor mechanical resilience. It is scientifically intriguing but remains unresolved whether and how the density limit of this class of cellular materials can be further pushed down while their mechanical resilience is being retained. In this work, a simple annealing strategy is developed to investigate the role of intersheet interactions in the formation of extreme-low-density of graphene-based cellular materials. It is discovered that the density limit of mechanically resilient cellular GEs can be further pushed down as low as 0.16 mg cm−3 through thermal annealing. The resultant extremely low density GEs reveal a range of unprecedented properties, including complete recovery from 98% compression in both of liquid and air, ultrahigh solvent adsorption capacity, ultrahigh pressure sensitivity, and light transmittance.Graphene cellular elastomers with a density as low as 0.16 mg cm−3 , super-compressability, ultrahigh solvent adsorption capacity, ultrahigh pressure sensitivity, and light transmittance can be fabricated by engineering the intersheet interactions of hierarchically structured graphene cellular materials.
      PubDate: 2017-07-21T06:17:11.683869-05:
      DOI: 10.1002/adma.201701553
       
  • Scaffold-Free Liver-On-A-Chip with Multiscale Organotypic Cultures
    • Authors: Yu-Shih Weng; Shau-Feng Chang, Ming-Cheng Shih, Shih-Heng Tseng, Chih-Huang Lai
      Abstract: The considerable advances that have been made in the development of organotypic cultures have failed to overcome the challenges of expressing tissue-specific functions and complexities, especially for organs that require multitasking and complex biological processes, such as the liver. Primary liver cells are ideal biological building blocks for functional organotypic reconstruction, but are limited by their rapid loss of physiological integrity in vitro. Here the concept of lattice growth used in material science is applied to develop a tissue incubator, which provides physiological cues and controls the 3D assembly of primary cells. The cues include a biological growing template, spatial coculture, biomimetic radial flow, and circulation in a scaffold-free condition. The feasibility of recapitulating a multiscale physiological structural hierarchy, complex drug clearance, and zonal physiology from the cell to tissue level in long-term cultured liver-on-a-chip is demonstrated. These methods are promising for future applications in pharmacodynamics and personal medicine.The concept of lattice growth is applied to develop a scaffold-free tissue incubator that provides physiological cues and controls the 3D assembly of primary cells. The feasibility of recapitulating a multiscale physiological structural hierarchy, complex drug clearance, and zonal physiology from the cell to tissue level in long-term cultured liver-on-a-chip is also demonstrated. These methods are promising for future applications in pharmacodynamics and personal medicine.
      PubDate: 2017-07-21T06:16:40.744131-05:
      DOI: 10.1002/adma.201701545
       
  • High-Yield Synthesis of Crystal-Phase-Heterostructured 4H/fcc Au@Pd
           Core–Shell Nanorods for Electrocatalytic Ethanol Oxidation
    • Authors: Ye Chen; Zhanxi Fan, Zhimin Luo, Xiaozhi Liu, Zhuangchai Lai, Bing Li, Yun Zong, Lin Gu, Hua Zhang
      Abstract: Noble-metal nanomaterials are attracting increasing research interest due to their promising applications in electrochemical catalysis, for example. Although great efforts have been devoted to the size-, shape-, and architecture-controlled synthesis of noble-metal nanomaterials, their crystal-phase-controlled synthesis is still in its infancy. Here, for the first time, this study reports high-yield synthesis of Au nanorods (NRs) with alternating 4H/face-centered cubic (fcc) crystal-phase heterostructures via a one-pot wet-chemical method. The coexistence of 4H and fcc phases is relatively stable, and the 4H/fcc Au NRs can serve as templates for crystal-phase-controlled epitaxial growth of other metals. As an example, bimetallic 4H/fcc Au@Pd core–shell NRs are synthesized via the epitaxial growth of Pd on 4H/fcc Au NRs. Significantly, the 4H/fcc Au@Pd NRs show superior mass activity toward the ethanol oxidation reaction, i.e., 6.2 and 4.9 times those of commercial Pd black and Pt/C catalysts, respectively. It is believed that this new synthetic strategy can be used to prepare other novel catalysts for various promising applications.High-yield crystal-phase-heterostructured 4H/fcc Au@Pd core–shell nanorods are successfully synthesized via a one-pot, facile, wet-chemical method. By using the 4H/fcc Au nanorod as a template, a 4H/fcc Au@Pd nanorod with epitaxially grown Pd shell is prepared, which exhibits superior electrocatalytic performance toward the ethanol oxidation reaction.
      PubDate: 2017-07-21T06:15:50.70393-05:0
      DOI: 10.1002/adma.201701331
       
  • Explosives in the Cage: Metal–Organic Frameworks for High-Energy
           Materials Sensing and Desensitization
    • Authors: Shan Wang; Qianyou Wang, Xiao Feng, Bo Wang, Li Yang
      Abstract: An overview of the current status of coordination polymers and metal–organic frameworks (MOFs) pertaining to the field of energetic materials is provided. The explosive applications of MOFs are discussed from two aspects: one for detection of explosives, and the other for explosive desensitization. By virtue of their adjustable pore/cage sizes, high surface area, tunable functional sites, and rich host–guest chemistry, MOFs have emerged as promising candidates for both explosive sensing and desensitization. The challenges and perspectives in these two areas are thoroughly discussed, and the processing methods for practical applications are also discussed briefly.Metal–organic frameworks (MOFs) are promising candidates for explosive sensing and desensitization due to their atomically designable and predicable structure, permanent porosity, controllable host–guest interactions, tunable inner-surface environment, and diversity of organic/metal building units. The recent developments, challenges, and perspectives in the strategies for explosive sensing and desensitization by MOFs are comprehensively discussed.
      PubDate: 2017-07-21T06:11:15.212743-05:
      DOI: 10.1002/adma.201701898
       
  • Polarized Light-Emitting Diodes Based on Patterned MoS2 Nanosheet Hole
           Transport Layer
    • Authors: Gyu Jin Choi; Quyet Van Le, Kyoung Soon Choi, Ki Chang Kwon, Ho Won Jang, Jin Seog Gwag, Soo Young Kim
      Abstract: Here, this study successfully fabricates few-layer MoS2 nanosheets from (NH4)2MoS4 and applies them as the hole transport layer as well as the template for highly polarized organic light-emitting diodes (OLEDs). The obtained material consists of polycrystalline MoS2 nanosheets with thicknesses of 2 nm. The MoS2 nanosheets are patterned by rubbing/ion-beam treatment. The Raman spectra shows that {poly(9,9-dioctylfluorene-alt-benzothiadiazole), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)]} (F8BT) on patterned MoS2 exhibits distinctive polarization behavior. It is discovered that patterned MoS2 not only improves the device efficiency but also changes the polarization behavior of the devices owing to the alignment of F8BT. This work demonstrates a highly efficient polarized OLED with a polarization ratio of 62.5:1 in the emission spectrum (166.7:1 at the peak intensity of 540 nm), which meets the manufacturing requirement. In addition, the use of patterned MoS2 nanosheets not only tunes the polarization of the OLEDs but also dramatically improves the device performance as compared with that of devices using untreated MoS2.Patterned MoS2 nanosheets obtained by rubbing/ion-beam treatment (RI-MoS2) can efficiently function as hole-transport layers and templates for alignment of an emissive layer {poly(9,9-dioctylfluorene-alt-benzothiadiazole), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT)} with a nematic-liquid-crystal phase toward highly efficient polarized organic light-emitting diodes. Interestingly, the RI-MoS2-based device exhibits an unprecedented average polarization ratio of 62.5:1 at the emitted wavelengths (166.7:1 at the peak intensity of 540 nm).
      PubDate: 2017-07-21T06:06:59.896973-05:
      DOI: 10.1002/adma.201702598
       
  • Dithiopheneindenofluorene (TIF) Semiconducting Polymers with Very High
           Mobility in Field-Effect Transistors
    • Authors: Hu Chen; Michael Hurhangee, Mark Nikolka, Weimin Zhang, Mindaugas Kirkus, Marios Neophytou, Samuel J. Cryer, David Harkin, Pascal Hayoz, Mojtaba Abdi-Jalebi, Christopher R. McNeill, Henning Sirringhaus, Iain McCulloch
      Abstract: The charge-carrier mobility of organic semiconducting polymers is known to be enhanced when the energetic disorder of the polymer is minimized. Fused, planar aromatic ring structures contribute to reducing the polymer conformational disorder, as demonstrated by polymers containing the indacenodithiophene (IDT) repeat unit, which have both a low Urbach energy and a high mobility in thin-film-transistor (TFT) devices. Expanding on this design motif, copolymers containing the dithiopheneindenofluorene repeat unit are synthesized, which extends the fused aromatic structure with two additional phenyl rings, further rigidifying the polymer backbone. A range of copolymers are prepared and their electrical properties and thin-film morphology evaluated, with the co-benzothiadiazole polymer having a twofold increase in hole mobility when compared to the IDT analog, reaching values of almost 3 cm2 V−1 s−1 in bottom-gate top-contact organic field-effect transistors.A novel bridged donor (TIF) with a large planar aromatic core is designed and synthesized using a novel intramolecular CH activation strategy. This TIF unit is copolymerized with BT, FBT, DFBT, and TT repeat units, with the TIF-BT copolymer exhibiting a higher p-type mobility (2.8 cm2 V−1 s−1) compared to previously reported IDT-BT and IDTT-BT copolymers using the same device-fabrication method.
      PubDate: 2017-07-21T06:05:45.275858-05:
      DOI: 10.1002/adma.201702523
       
  • Probing Anisotropic Thermal Conductivity of Transition Metal
           Dichalcogenides MX2 (M = Mo, W and X = S, Se) using Time-Domain
           Thermoreflectance
    • Authors: Puqing Jiang; Xin Qian, Xiaokun Gu, Ronggui Yang
      Abstract: Transition metal dichalcogenides (TMDs) are a group of layered 2D semiconductors that have shown many intriguing electrical and optical properties. However, the thermal transport properties in TMDs are not well understood due to the challenges in characterizing anisotropic thermal conductivity. Here, a variable-spot-size time-domain thermoreflectance approach is developed to simultaneously measure both the in-plane and the through-plane thermal conductivity of four kinds of layered TMDs (MoS2, WS2, MoSe2, and WSe2) over a wide temperature range, 80–300 K. Interestingly, it is found that both the through-plane thermal conductivity and the Al/TMD interface conductance depend on the modulation frequency of the pump beam for all these four compounds. The frequency-dependent thermal properties are attributed to the nonequilibrium thermal resistance between the different groups of phonons in the substrate. A two-channel thermal model is used to analyze the nonequilibrium phonon transport and to derive the intrinsic thermal conductivity at the thermal equilibrium limit. The measurements of the thermal conductivities of bulk TMDs serve as an important benchmark for understanding the thermal conductivity of single- and few-layer TMDs.Anisotropic thermal conductivities of layered 2D crystals (MoS2, MoSe2, WS2, and WSe2) are measured using a variable-spot-size time-domain thermoreflectance approach at 80–300 K. Non-equilibrium thermal transport between the high-frequency and the low-frequency phonons is observed in the measurement results, and a two-temperature model is used to extract the intrinsic thermal-conductivity values (at the equilibrium limit).
      PubDate: 2017-07-20T04:05:40.679247-05:
      DOI: 10.1002/adma.201701068
       
  • N-Type Organic Thermoelectrics: Improved Power Factor by Tailoring
           Host–Dopant Miscibility
    • Authors: Jian Liu; Li Qiu, Giuseppe Portale, Marten Koopmans, Gert ten Brink, Jan C. Hummelen, L. Jan Anton Koster
      Abstract: In this contribution, for the first time, the polarity of fullerene derivatives is tailored to enhance the miscibility between the host and dopant molecules. A fullerene derivative with a hydrophilic triethylene glycol type side chain (PTEG-1) is used as the host and (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine n-DMBI) as the dopant. Thereby, the doping efficiency can be greatly improved to around 18% (
      PubDate: 2017-07-19T06:47:10.35965-05:0
      DOI: 10.1002/adma.201701641
       
  • Preventing Thin Film Dewetting via Graphene Capping
    • Authors: Peigen Cao; Peter Bai, Arash A. Omrani, Yihan Xiao, Kacey L. Meaker, Hsin-Zon Tsai, Aiming Yan, Han Sae Jung, Ramin Khajeh, Griffin F. Rodgers, Youngkyou Kim, Andrew S. Aikawa, Mattew A. Kolaczkowski, Yi Liu, Alex Zettl, Ke Xu, Michael F. Crommie, Ting Xu
      Abstract: A monolayer 2D capping layer with high Young's modulus is shown to be able to effectively suppress the dewetting of underlying thin films of small organic semiconductor molecule, polymer, and polycrystalline metal, respectively. To verify the universality of this capping layer approach, the dewetting experiments are performed for single-layer graphene transferred onto polystyrene (PS), semiconducting thienoazacoronene (EH-TAC), gold, and also MoS2 on PS. Thermodynamic modeling indicates that the exceptionally high Young's modulus and surface conformity of 2D capping layers such as graphene and MoS2 substantially suppress surface fluctuations and thus dewetting. As long as the uncovered area is smaller than the fluctuation wavelength of the thin film in a dewetting process via spinodal decomposition, the dewetting should be suppressed. The 2D monolayer-capping approach opens up exciting new possibilities to enhance the thermal stability and expands the processing parameters for thin film materials without significantly altering their physical properties.A monolayer 2D capping layer is shown to be able to effectively suppress the dewetting of thin films of both polymer and polycrystalline metal. Thermodynamic modeling indicates that the exceptionally high Young's modulus and surface conformity of 2D capping layers such as graphene and MoS2 substantially suppress surface fluctuations and thus dewetting.
      PubDate: 2017-07-19T06:40:42.385202-05:
      DOI: 10.1002/adma.201701536
       
  • Engineering Single Nanopores on Gold Nanoplates by Tuning Crystal Screw
           Dislocation
    • Authors: Yueming Zhai; Fan Zhang, Bo Zhang, Xiaohu Gao
      Abstract: Compared with the large variety of solid gold nanostructures, synthetic approaches for their hollow counterparts are limited, largely confined to chemical and irradiation-based etching of preformed nanostructures. In particular, the preparation of through nanopore structures is extremely challenging. Here, a unique strategy for direct synthesis of gold nanopores in solution without the need for sacrificial templates or postsynthesis processing is reported. By controlling the degree of crystal screw dislocation, a single through pore with diameter ranging from sub-nanometer to tens of nanometers, in the center of large gold nanoplates, can be engineered with precision. Ionic current rectification behaviors are observed using the gold nanopore, potentially enabling new capabilities in biosensing, sequencing, and imaging.High-throughput production of solid-state nanopores is a major challenge. A novel methodology is reported for solution-phase synthesis of Au nanoplates with a single through pore with diameters ranging from sub-nanometers to tens of nanometers in the center, based on crystal screw dislocation.
      PubDate: 2017-07-19T01:36:11.764447-05:
      DOI: 10.1002/adma.201703102
       
  • Engineering the Surface of Smart Nanocarriers Using a
           pH-/Thermal-/GSH-Responsive Polymer Zipper for Precise Tumor Targeting
           Therapy In Vivo
    • Authors: Penghui Zhang; Yan Wang, Jing Lian, Qi Shen, Chen Wang, Bohan Ma, Yuchao Zhang, Tingting Xu, Jianxin Li, Yongping Shao, Feng Xu, Jun-Jie Zhu
      Abstract: Nanocarrier surface chemistry plays a vital role in mediating cell internalization and enhancing delivery efficiency during in vivo chemotherapy. Inspired by the ability of proteins to alter their conformation to mediate functions, a pH-/thermal-/glutathione-responsive polymer zipper consisting of cell-penetrating poly(disulfide)s and thermosensitive polymers bearing guanidinium/phosphate (Gu+/pY−) motifs to spatiotemporally tune the surface composition of nanocarriers for precise tumor targeting and efficient drug delivery is developed. Surface engineering allows the nanocarriers to remain undetected during blood circulation and favors passive accumulation at tumor sites, where the acidic microenvironment and photothermal heating break the pY−/Gu+ binding and rupture the zipper, thereby exposing the penetrating shell and causing enhanced cellular uptake via counterion-/thiol-/receptor-mediated endocytosis. The in vivo study demonstrates that by manipulating the surface states on command, the nanocarriers show longer blood circulation time, minimized uptake and drug leakage in normal organs, and enhanced accumulation and efficient drug release at tumor sites, greatly inhibiting tumor growth with only slight damage to normal tissues. If integrated with a photothermal dye approved by the U.S. Food and Drug Administration (FDA), polymer zipper would provide a versatile protocol for engineering nanomedicines with high selectivity and efficiency for clinical cancer treatment.pH-/thermal-/glutathione-responsive polymer zippers are screened and explored to tune nanocarrier surface compositions on command for precise tumor targeting in vivo. The nanocarriers remain stealthy during blood circulation, but their surfaces are activated by the acidic microenvironment and photothermal heating at tumor sites for enhanced cellular uptake and efficient drug release, presenting a versatile engineering strategy for nanomedicinal use.
      PubDate: 2017-07-18T02:41:59.883386-05:
      DOI: 10.1002/adma.201702311
       
  • In Situ Two-Step Photoreduced SERS Materials for On-Chip Single-Molecule
           Spectroscopy with High Reproducibility
    • Authors: Wenjie Yan; Longkun Yang, Jianing Chen, Yaqi Wu, Peijie Wang, Zhipeng Li
      Abstract: A method is developed to synthesize surface-enhanced Raman scattering (SERS) materials capable of single-molecule detection, integrated with a microfluidic system. Using a focused laser, silver nanoparticle aggregates as SERS monitors are fabricated in a microfluidic channel through photochemical reduction. After washing out the monitor, the aggregates are irradiated again by the same laser. This key step leads to full reduction of the residual reactants, which generates numerous small silver nanoparticles on the former nanoaggregates. Consequently, the enhancement ability of the SERS monitor is greatly boosted due to the emergence of new “hot spots.” At the same time, the influence of the notorious “memory effect” in microfluidics is substantially suppressed due to the depletion of surface residues. Taking these advantages, two-step photoreduced SERS materials are able to detect different types of molecules with the concentration down to 10−13m. Based on a well-accepted bianalyte approach, it is proved that the detection limit reaches the single-molecule level. From a practical point of view, the detection reproducibility at different probing concentrations is also investigated. It is found that the effective single-molecule SERS measurements can be raised up to ≈50%. This microfluidic SERS with high reproducibility and ultrasensitivity will find promising applications in on-chip single-molecule spectroscopy.On-chip single-molecule surface-enhanced Raman scattering (SERS) monitors free of the “memory effect” are fabricated in microfluidics by the two-step photoreduction method. Proved by bianalyte statistics, on-chip single-molecule detection is accomplished. This is a quick and well-reproducible microfluidic SERS technique with detection limit as low as 10−13m. At the single-molecule level, the detection reproducibility can reach up to 50%.
      PubDate: 2017-07-18T02:40:46.980172-05:
      DOI: 10.1002/adma.201702893
       
  • Strongly Enhanced Photovoltaic Performance and Defect Physics of
           Air-Stable Bismuth Oxyiodide (BiOI)
    • Authors: Robert L. Z. Hoye; Lana C. Lee, Rachel C. Kurchin, Tahmida N. Huq, Kelvin H. L. Zhang, Melany Sponseller, Lea Nienhaus, Riley E. Brandt, Joel Jean, James Alexander Polizzotti, Ahmed Kursumović, Moungi G. Bawendi, Vladimir Bulović, Vladan Stevanović, Tonio Buonassisi, Judith L. MacManus-Driscoll
      Abstract: Bismuth-based compounds have recently gained increasing attention as potentially nontoxic and defect-tolerant solar absorbers. However, many of the new materials recently investigated show limited photovoltaic performance. Herein, one such compound is explored in detail through theory and experiment: bismuth oxyiodide (BiOI). BiOI thin films are grown by chemical vapor transport and found to maintain the same tetragonal phase in ambient air for at least 197 d. The computations suggest BiOI to be tolerant to antisite and vacancy defects. All-inorganic solar cells (ITO NiOx BiOI ZnO Al) with negligible hysteresis and up to 80% external quantum efficiency under select monochromatic excitation are demonstrated. The short-circuit current densities and power conversion efficiencies under AM 1.5G illumination are nearly double those of previously reported BiOI solar cells, as well as other bismuth halide and chalcohalide photovoltaics recently explored by many groups. Through a detailed loss analysis using optical characterization, photoemission spectroscopy, and device modeling, direction for future improvements in efficiency is provided. This work demonstrates that BiOI, previously considered to be a poor photocatalyst, is promising for photovoltaics.Bismuth oxyiodide (BiOI) is demonstrated to be defect-tolerant, with the bulk phase unchanged after 197 d in ambient air. In solar cells, up to 80% external quantum efficiency is achieved. The short-circuit current densities and power conversion efficiencies are nearly double previous reports of photovoltaics based on BiOI, as well as other recently explored bismuth halides and chalcohalides.
      PubDate: 2017-07-17T08:13:41.819583-05:
      DOI: 10.1002/adma.201702176
       
  • Biotransporting Self-Assembled Nanofactories Using Polymer Vesicles with
           Molecular Permeability for Enzyme Prodrug Cancer Therapy
    • Authors: Tomoki Nishimura; Yoshihiro Sasaki, Kazunari Akiyoshi
      Abstract: As “biotransporting nanofactories”, in vivo therapeutic biocatalyst nanoreactors would enable encapsulated enzymes to transform inert prodrugs or neutralize toxic compounds at target disease sites. This would offer outstanding potential for next-generation therapeutic platforms, such as enzyme prodrug therapy. Designing such advanced materials has, however, proven challenging. Here, it is shown that self-assembled nanofactories formulate with polymeric vesicles with an intrinsically permeable membrane. The vesicles, CAPsomes, are composed of carbohydrate-b-poly(propylene glycol) and show molecular-weight-depended permeability. This property enables CAPsomes to act as biocatalyst nanoreactors, protecting encapsulated enzymes from degradation while acting on low-molecular-weight substrates. In tumor bearing mice, combined treatment with enzyme-loaded CAPsomes and doxorubicin prodrug inhibit tumor growth in these mice without any observable toxicity. The results demonstrate, for the first time, in vivo therapeutic efficacy of CAPsomes as nanofactories for enzyme prodrug cancer therapy.Self-assembled nanofactories formulated with intrinsically molecular permeable polymer vesicles are reported. The vesicles are composed of maltooligosaccharide-b-poly(propylene glycol) and have molecular-weight-dependent permeable membrane. Because of this permeability, the vesicles serve as nanofactories that can transform prodrugs into drugs in vivo for cancer therapy.
      PubDate: 2017-07-17T02:11:19.048767-05:
      DOI: 10.1002/adma.201702406
       
 
 
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