Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shelling with MoS$_2$ Functional CuS@MoS2 Hybrids as Electrocatalysts
  for the Oxygen Reduction and Hydrogen Evolution Reactions   The development of noble-metal free electrocatalysts is of high importance
for clean energy conversion applications. MoS$_2$ has been considered as a
promising low cost catalyst for the hydrogen evolution reaction (HER), however
its activity is limited by poor conductivity and low abundance of active sites.
Moreover, its suitability as an effective catalyst for other reactions, in
particluar the oxygen reduction reaction (ORR), was hardly explored to date.
Herein, we show hybrid nanostructures of shelled CuS particles with MoS$_2$
layers, which produces several outcomes: The MoS$_2$ shell is strained and
defective, and charge transfer from the core to MoS$_2$ occurs, enabling
activation of the basal plane of MoS$_2$. Changing the feed ratio of the
precursors led to control over morphology, such that the wrapping of the cores
with the shell was continuously varied and characterized. We found an optimal
hybrid structure, which provided high electrochemical active surface area and
fast charge transfer kinetics, leading to improved activity not only towards
HER (overpotential of 225 mV at 10 mA cm$^{-1}$), but also for the sluggish ORR
(onset potential 0.87 V vs RHE).

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The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: stat
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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin
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The categories of this paper are: supr-con
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The categories of this paper are: astro-ph