Exploring the underlying oxygen reduction reaction electrocatalytic activities of pyridinic-N and pyrrolic-N doped graphene quantum dots

In this study, density functional theory was used to investigate the differences of oxygen reduction reaction catalytic activities between pyridinic-N and pyrrolic-N doped graphene quantum dots (GQDs) and the influence of four ions/groups: OH–, H3O+, OH and H3O on their electronic properties. Free energy change calculations show that pyridinic-N doped GQDs (pN-GQDs) have better catalytic activities than pyrrolic-N doped GQDs (prN-GQDs). Moreover, the catalytic activity of both pN-GQDs and prN-GQDs can be enhanced via the functionalization of OH and H3O groups, which greatly alters electronic structures of the GQDs and thereby the adsorption strength of reactants can be effectively controlled. The findings can shed light on the effects of different N doping configurations and adsorbed species on electrocatalytic activities and provide theoretical guidelines for design and development of carbon-based oxygen reduction reaction electrocatalysts for fuel cells and metal-air batteries.