Fig. 6: Density functional theory calculations and analysis of N1S1@CF.

Schematic structures of a graphite-N@C, b pyridine-N@C, c pyrrole-N@C, d thiophene-S@C, and e N1S1@C with the active sites used for the calculations marked by red circles, and ORR Gibbs free energies (f) and relative energies (g) are indicated. h Schematic representation of the electron transfer pathway for the ORR.