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

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 O-2 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 (O-2) 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.