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Caption : figure s1 several possible p, n co-doped configurations and corresponding formation energies.

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Caption : figure s2 pn-gra structure from the molecular dynamics simulation (1000 k, nvt) at (a) 500 fs, (b) 1000 fs, (c) 1500 fs, (d) 2000 fs, (e) 2500 fs and (f) 3000 fs. all bond distances are in å.

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Caption : figure s3 several possible adsorption configurations of o2 on pn-gra and corresponding adsorption energies.

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Caption : figure s4 structure of o2 adsorbed on pn-gra (side-on) from the molecular dynamics simulation (353 k, nvt) at (a) 500 fs, (b) 1000 fs, (c) 1500 fs, (d) 2000 fs, (e) 2500 fs and (f) 3000 fs.

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Caption : figure s5 structures of o2 adsorbed on pn-gra (end-on) from the molecular dynamics simulation (353 k, nvt).

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Caption : figure s5 structures of o2 adsorbed on pn-gra (end-on) from the molecular dynamics simulation (353 k, nvt).

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Caption : figure s6 o2 adsorption configuration and corresponding adsorption energy of (a) p-gra and (b) n-gra.

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Caption : figure s7 free energy diagram for orr on (a) p-gra and (c) n-gra at the equilibrium potential (u=1.23 v).

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Caption : figure s8 electronic density of states (dos) of (a) p-gra, (b) n-gra and pn-gra, the dashed line at zero energy represents the fermi level.