A potential-driven switch of activity promotion mode for the oxygen evolution reaction at Co3O4/NiOxHy interface

Co3O4 spinel oxides have manifested promising activity toward the oxygen evolution reaction (OER) through effective modifications. For them to become top electrocatalysts, however, accurate accounts of the catalytic kinetics are essential to gain a deep understanding of the activity promotion mechanisms. Herein, we use a newly proposed kinetic model based on energetic span as the rate-determining term for the electrocatalytic reaction to throw light on the promotion mechanism of Co3O4 interfaced with nickel hydroxides (NiOxHy) for the OER. We find that depending on the electrode potential, the OER kinetics at the designed interface between Co3O4 and NiOxHy are boosted in entirely different ways. As a result, the OER can occur at a lower onset potential as well as a low Tafel slope. This work emphasizes the benefit of using rational theoretical models for electrocatalyst design.