Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 3D arrangement of epitaxial graphene conformally grown on porousified
  crystalline SiC   Nanoporous materials represent a versatile solution for a number of
applications ranging from sensing, energy applications, catalysis, drug
delivery, and many others. The synergy between the outstanding properties of
graphene with a three-dimensional porous structure, circumventing the limits of
its 2D nature, constitutes therefore a breakthrough for many fields. We report
the first three-dimensional growth of epitaxial graphene on a porousified
crystalline 4H-SiC(0001). The wafer porosification is performed via a sequence
of metal-assisted photochemical and photoelectrochemical etching in
hydrofluoric acid based electrolytes. Pore dimensions of the matrix have been
evaluated by electron tomography resulting in an average diameter of 180 nm.
Graphene growth is performed in an ultra high vacuum environment at a base
pressure of $10^{-11}$ mbar. The graphene growth inside the pores is uniform as
confirmed by Transmission Electron Microscopy (TEM) analysis. Raman
spectroscopy confirms the high quality of the graphene with a 2D/G ratio $>1$
and an average graphene crystal size of $\approx$ 100 nm. Furthermore, it
demonstrates a uniform coverage of graphene across the whole sample area. The
surface-to-volume ratio of this novel material, its properties, the tunability
of the pore size and the scalability of the surface porosification process
offer a game changing perspective for a large number of applications.

2
The categories of this paper are: math
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an