The mechanism study of oxygen reduction reaction (ORR) on non-equivalent P, N co-doped graphene

Abstract The density functional theory (DFT) calculations in this study were applied to investigate the oxygen reduction reaction (ORR) mechanism of non-equivalent P, N co-doped graphene. The simulation results showed that the formation of sp3 hybridization was energetically more profitable than that of the sp3d hybridized doped form. O2 molecules directly dissociated on G-PN2C1 and G-PN3 by following the Eley-Rideal (ER) mechanism, which involves H2O formation by reaction with H+ from the electrolyte. Furthermore, G-PN3 was found to perform better as ORR catalysts in an acidic medium due to their low overpotentials of 0.419V. In contrast, G-PN3C1 and G-PN4 tended to follow the OOH* formation pathway, which showed a higher overpotential for the ORR. X-ray photoelectron spectroscopy (XPS) analysis and electrochemical experiments were performed to verify the calculation results, which indicated that the appropriate proportions of G-PN3 led to greatly improved ORR performance in the following order: G-N