Tailoring Surface Electronic Structure of Spinel Co₃O₄ Oxide via Fe and Cu Substitution for Enhanced Oxygen Evolution Reaction

Multimetal spinel oxides are promising candidates for the oxygen evolution reaction (OER) due to their ability to offer more accessible active sites and oxygen vacancies (O_vac). However, the utilization of redox-active species in spinel oxides is limited. Herein, we unveil an efficient multimetal spinel oxide using high-throughput methods. The oxide contains Fe and Cu substituted into Co sites following a stoichiometry of Fe_0.6Cu_0.6Co_1.8O₄. The dual cation substitution of Fe and Cu manipulates the electronic states and generates O_vac, thereby generating more accessible active species. This significantly improves the OH^- adsorption capacity on spinel oxide triggering a more favorable OER reaction with a low overpotential of 265 mV at 10 mA cm^-2 and high durability in an alkaline medium. Our work not only presents the utilization of a high-throughput approach to explore efficient catalysts with optimal composition but also provides useful insights into the modulation of electronic states for enhanced catalytic performance.