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 Co 3 O 4 catalyst enriched with O v (Ru–Co 3 O 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–Co 3 O 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–Co 3 O 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.