Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Activation of Graphenic Carbon due to Substitutional Doping by Nitrogen:
  Mechanistic Understanding from First-principles   Nitrogen doped graphene and carbon nanotubes are popularly in focus as
metal-free electro-catalysts for oxygen reduction reactions (ORR) central to
fuel-cells. N doped CNTs have been also reported to chemisorb mutually,
promising a route to their robust pre-determined assembly into devices and
mechanical reinforcements. We propose from first-principles a common
mechanistic understanding of these two aspects pointing further to a generic
chemical activation of carbon atoms due to substitution by nitrogen in
experimentally observed configurations. Wannier-function based orbital resolved
study of mechanisms suggests increase in C-N bond-orders in attempt to retain
$\pi$-conjugation among carbon atoms, causing mechanical stress and loss of
charge neutrality of nitrogen and carbon atoms, which remedially facilitate
chemical activation of N coordinated C atoms, enhancing sharply with increasing
coordination to N and proximity to zigzag edges. Activated C atoms facilitate
covalent adsorption of radicals in general, diradicals like O$_2$ relevant to
ORR, and also other similarly activated C atoms leading to self-assembly of
graphenic nano-structures, while remaining inert to ordinary graphenic C atoms.

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The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
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The categories of this paper are: stat
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
0
The categories of this paper are: hep-ph