Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Covalent Hybrid of Spinel Manganese-Cobalt Oxide and Gra-phene as
  Advanced Oxygen Reduction Electrocatalysts
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int