Decoupling the Effects of Ruthenium Sites and Oxygen Vacancies on the Mechanism Regulation of Acidic Water Oxidation

Precise regulation of the oxygen evolution reaction (OER) pathway to a more favorable lattice oxygen mechanism (LOM) is essential for achieving high-performance acidic OER electrocatalysts. Although cation doping and oxygen vacancy (O_v) engineering are fundamental strategies, their individual contributions to activating the LOM mechanism remain unclear. Herein, we report a Ru-doped Co₃O₄ catalyst enriched with O_v (Ru–Co₃O_4–x) as the model system to decouple these effects. Combined experimental characterizations and density functional theory (DFT) calculations reveal that O_v can exclusively promote the LOM mechanism, while Ru dopants minimally alter the catalytic pathway. The incorporation of Ru enables the electron redistribution within the lattice of Ru–Co₃O_4–x, enhancing the adsorption of key reaction intermediates, thereby lowering the reaction energy barriers. The electron localization at Ru sites is also responsible for improved stability in harsh conditions. As a result, Ru–Co₃O_4–x delivers a relatively low overpotential of 198 mV at 10 mA cm^–2 and is capable of operating stably for more than 220 h. Our findings not only underscore the synergistic effects of Ru doping and O_v incorporation in enhancing acidic OER performance but also decouple the effects of Ru sites and oxygen vacancies on the mechanism regulation, providing valuable guidance for designing and optimizing high-performance acidic OER catalysts.