Interface Engineering of Oxygen Vacancy-Enriched Ru/RuO2-Co3O4 Heterojunction for Efficient Oxygen Evolution Reaction in Acidic Media

RuO2 is currently regarded as a benchmark electrocatalyst for water oxidation in acidic media. However, its wide application is still restricted by limited durability and high cost. Herein, we report a Ru/RuO2-Co3O4 catalyst for boosting the acidic oxygen evolution reaction catalytic performance via constructing a heterointerface between RuO2 and Co3O4 and vacancy engineering. The resulting Ru/RuO2-Co3O4 shows a 226 mV overpotential at 10 mA cm-2 and excellent stability with a small overpotential increase after continuous testing for 19 h, greatly surpassing that of commercial RuO2 in a 0.1 M HClO4 solution. Depth structure characterizations involved in XPS, XANES, and EXAFS indicate that the favorable catalytic performance of Ru/RuO2-Co3O4 is mainly ascribed to the interfacial charge transfer by heterojunction interfaces between Co species and Ru species. Co3O4 is adjacent to RuO2 and donates electrons, making the valence state of Ru lowered and the Ru-O covalency weakened, which greatly suppress the dissolution of Ru and thus enhance stability. Meanwhile, the existing oxygen vacancies improve the intrinsic catalytic activity. This study is highly expected to favor the design and synthesis of more highly efficient electrocatalysts applied in energy-related devices.