Promoting Oxygen Evolution Reactions through Introduction of Oxygen Vacancies to Benchmark NiFe–OOH Catalysts

Advanced electrocatalysts toward oxygen evolution reaction (OER) at high current density with low overpotential remain a significant challenge for electrochemical water splitting. Herein, NiFe-based catalysts with appropriate electronic conductivity and catalytic activity have been obtained through introduction of oxygen vacancies by a facile and economic NaBH4 reduction approach. The combined density functional theory calculations, physical characterization, and electrochemical studies disclose that the reductive treatment creates a high amount of oxygen vacancies, high active sites, and a low energy barrier for OER. The oxygen vacancy-rich catalyst yields a more than 2-fold increased current density (from 100 to 240 mA cm-2) at a low overpotential of 270 mV, accompanied by good stability under OER conditions. The approach is also broadly applicable for NiFe compounds synthesized via different methods or substrates.