Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Doped graphene/carbon black hybrid catalyst giving enhanced oxygen
  reduction reaction activity with high resistance to corrosion in proton
  exchange membrane fuel cells
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas