Ruthenium Single‐Atom Modulated Protonated Iridium Oxide for Acidic Water Oxidation in Proton Exchange Membrane Electrolysers

Abstract Proton exchange membrane water electrolysers promise to usher in a new era of clean energy, but they remain a formidable obstacle in designing active and durable electrocatalysts for the acidic oxygen evolution reaction (OER). In this study, a protonated iridium oxide embedded with single‐atom dispersed ruthenium atoms (H_3.8Ir_1−xRu_xO₄) that demonstrates exceptional activity and stability in acidic water oxidation is introduced. The single Ru dopants favorably induce localized oxygen vacancies in the Ir─O lattice, synergistically strengthening the adsorption of OOH* intermediates and enhancing the intrinsic OER activity. In addition, the preferential oxidation of Ru and the electronegativity of the oxygen vacancies significantly stabilize the Ir─O active sites, improving the OER stability. Consequently, the H_3.8Ir_1─xRu_xO₄ catalyst shows an overpotential of 255 mV at 10 mA cm⁻² and displays exceptional catalytic endurance in acidic electrolytes, surpassing 1100 h, representing a remarkable one‐order‐of‐magnitude increase in stability compared to that of pristine H_3.8IrO₄. A proton exchange membrane electrolyser utilizing the H_3.8Ir_1−xRu_xO₄ catalyst as an anode exhibits stable performance for more than 1280 h under a high current density of 2 A cm⁻².