Effects of Doped N, B, P, and S Atoms on Graphene toward Oxygen Evolution Reactions.

Abstract

Molecular oxygen and hydrogen can be obtained from the water-splitting process through the electrolysis technique. However, harnessing energy is very challenging in this way due to the involvement of the 4e– reaction pathway, which is associated with a substantial amount of reaction barrier. After the report of the first N-doped graphene acting as an oxygen reduction reaction catalyst, the scientific community set out on exploring more reliable doping materials, better material engineering techniques, and developing computational models to explain the interfacial reactions. In this study, we modeled the graphene surface with four different nonmetal doping atoms N, B, P, and S individually by replacing a carbon atom from one of the graphitic positions. We report the mechanism of the complete catalytic cycle for each of the doped surfaces by the doping atom. The energy barriers for individual steps were explored using the biased first-principles molecular dynamics simulations to overcome the high reaction barrier. We explain the active sites and provide a comparison between the activation energy obtained by the application of two computational methods. Observing the rate-determining step, that is, oxo–oxo bond formation, S-doped graphene is the most effective. In contrast, N-doped graphene seems to be the least useful for oxygen evolution catalysis compared to the undoped graphene surface. B-doped graphene and P-doped graphene have an equivalent impact on the catalytic cycle.