Computational Insight into TM–N_<i>x</i> Embedded Graphene Bifunctional Electrocatalysts\nfor Oxygen Evolution and Reduction Reactions

Abstract

Due to the energy\ncrisis, development of bifunctional electrocatalysts\nfor both oxygen evolution and reduction reactions is highly demanding.\nIn this study, we have systematically investigated the bifunctional\nactivity of metal (Co/Rh/Ir) and N co-doped graphene systems with\nvarying N-dopant concentrations (TM–N_<i>x</i>@G, <i>x</i> = 0, 2, 4) using first-principles calculations.\nCharge transfer from the metal sites to the adsorbed intermediates\nand the adsorption free energy of the intermediates play important\nroles to help understand the potential-determining step and overpotential\nvalues for oxygen evolution reaction (OER)/oxygen reduction reaction\n(ORR). A dual volcano plot for all the systems using a common descriptor\nΔ<i>G</i>_OH* has been constructed. We find\nthat the systems having Δ<i>G</i>_OH* values\nin the range of 0.40–0.70 eV can act as bifunctional electrocatalysts.\nOur study not only highlights the importance of metal and non-metal\nco-doped graphene as bifunctional catalysts but also can serve as\na promising strategy for the design of efficient OER/ORR electrocatalysts.