Mechanisms insight into oxygen reduction reaction on sulfur-doped Fe–N2 graphene electrocatalysts

Abstract The density functional theory (DFT) calculations were performed to investigate the stability of the S-doped Fe–N2G electrocatalysts, as well as ORR mechanism and activity. The most stable configuration is the Fe–N2S1G because of forming a strong bond structure of Fe–S. In addition, the structures of Fe–N2S3G and Fe–N2S4G also exhibit the higher stability compared to the undoped Fe–N2G. According to the distinct charge difference on the surface, the O-contained intermediates would like to adsorb on the active sites of Fe–N2 complex active sites. The binding strength of OH on these different catalysts follows the increasing order of Fe–N2S4G