Acid-Treated RuO2/Co3O4 Nanostructures for Acidic Oxygen Evolution Reaction Electrocatalysis

RuO2 is widely used as an acidic electrocatalyst to achieve high catalytic activity, but the severe leaching and scarcity of the Ru element restrict application on a large scale. Strategies such as designing nanostructures and adjusting metals' electronic properties to regulate the adsorption of reaction intermediates can be used for the design and preparation of catalysts. Herein, we designed an acid-treated RuO2/Co3O4 nanostructure electrocatalyst with low Ru content and an intimate heterogeneous interface to disrupt the trade-off relationship between stability and activity. The resulting acid-treated RuO2/Co3O4 displayed an overpotential of 152 mV in a 0.5 M H2SO4 electrolyte, greatly exceeding that of commercial RuO2 (221 mV). Despite continuous operation for 150 h, it still exhibited good stability with a degradation rate of 0.67 mV·h–1. Multiple characterization analyses revealed that an electron transfer occurs from Ruoct to Cooct(III) sites through the mutual O atoms in acid-treated RuO2/Co3O4, which is further strengthened by the presence of oxygen vacancies. The oxygen vacancy and heterogeneous interface synergistically regulate electronic dispersion, optimize the adsorption of the oxygen intermediates (*OOH), and improve the reaction kinetics of the oxygen evolution reaction (OER). This work brings to light the significance of oxygen vacancies for modulating the electronic structure of RuO2 nanoparticles and enhancing stability on Co3O4 support, thus highlighting the use of nanostructure and interfacial engineering to achieve better acidic OER catalyst design.