Silicon-Doped Nitrogen-Coordinated Graphene as Electrocatalyst for Oxygen Reduction Reaction

Abstract

For large-scale commercial applications of fuel cells, it is necessary to develop carbon-based metal-free electrocatalysts that are highly durable, cost-effective, and environmentally benign for oxygen reduction reaction (ORR). Here, using first principles simulations, we have explored the potential of silicon-doped nitrogen-coordinated graphene (Si-GN4) system as an efficient electrocatalyst for ORR in a fuel cell in acidic environment. Introduction of different electronegative atoms (Si, N) on graphene surface facilitates the activation of O2 and desorption of H2O from the surface, which are the two key steps for a good ORR catalyst. The plausible reaction pathways are studied, and it is revealed that the reaction mainly occurs via 4e– reduction pathway following associative approach. Least stabilization of HOOH on Si-GN4 surface ruled out the possibility of 2e– reduction pathway. Hydrogenation of oxygen (O2) is found to be the kinetically rate-determining step. Our computational study reveals that Si-GN4 surface is quite a promising catalyst with high efficiency for ORR in fuel cells.