Theoretical insights into the dual-site oxygen evolution reaction mechanism on Co-N-C single atom catalysts

Single-atom catalysts (SACs) possess unique catalytic properties due to their low-coordination and unsaturated active sites, and are widely applied in the field of the oxygen evolution reaction (OER). Limited by the same type of active sites and their associated adsorption-evolution mechanism (AEM), introducing new active sites and synergistic reaction mechanisms can effectively enhance the activity of SACs. Herein, density functional theory was used to study the possibility of carbon atoms serving as synergistic sites in the CoN4 embedded graphene system. The results show that the intermediate *OC on the carbon site can accept protons from *OOH formed on the Co site. Through the synergistic evolution of the dual-sites, the overpotential is reduced to 0.27 V. Subsequently, by doping with graphitic N species, the activity of the system is further enhanced, and the overpotential approaches the theoretical limit. Our work reveals the remarkable potential of carbon atoms as synergistic sites in carbon-based catalysts for oxygen electrocatalysis, providing new ideas for the development of more single-atom carbon-based catalysts in the future.