Acid-Treated RuO₂/Co₃O₄ Nanostructures for Acidic OxygenEvolution Reaction Electrocatalysis

Abstract

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 Ru_oct to Co_oct(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.