Density Functional Theory Studies of Heteroatom-Doped Graphene-like GaN Monolayers as Electrocatalysts for Oxygen Evolution and Reduction

Single-atom catalysts (SACs) supported on two-dimensional (2D) nanomaterials with high activity for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) are highly desirable for renewable energy applications. Herein, we systemically investigate the electrocatalytic properties of transition metal atom-doped graphene-like GaN(g-GaN) monolayers by means of density functional theory. Our results reveal that Fe/g-GaN, Ni/g-GaN, and Au/g-GaN can be high-activity bifunctional electrocatalysts. Specifically, the Ni/g-GaN overpotential for the OER/ORR is estimated as 0.26/0.38 V, suggesting its extremely high catalytic performance. As an efficient descriptor for the adsorption strength of reactions on substrates, the TM atom d-band centers are found to linearly correlate with Gibbs free energies of HO* and HOO* species. This work provides an effective guidance to design high-activity SACs for the OER and ORR.