Abstract: The development of anode catalysts that combine high activity, high stability, and low iridium loading is key to advancing the large-scale application of proton exchange membrane water electrolysis for hydrogen production. Therefore, this study proposes a strategy to construct Ta-IrO₂ catalysts rich in oxygen vacancies (O_V) by doping high-valent tantalum (Ta) into iridium dioxide using a modified Adams fusion method. Doping of Ta⁵⁺ introduced a high concentration of oxygen vacancies into the Ta-IrO₂ catalyst, effectively enhancing its catalytic activity. This enabled the catalyst to exhibit excellent electrocatalytic performance in the acidic oxygen evolution reaction, with an overpotential of only 196 mV at a current density of 10 mA·cm^-2, which is lower than that of commercial IrO₂ (289 mV), and a lower Tafel slope (47.13 mV·dec^-1), indicating faster reaction kinetics, and a high mass activity (1.6 V, 2187 mA·mg_Ir^-1). Furthermore, the formed Ta-O bonds effectively stabilize the catalytic sites, enabling the Ta-IrO₂ catalyst to operate stably for 450 h at 10 mA·cm^-2, demonstrating excellent durability. Additionally, the iridium loading of 0.13 mg_Ir·cm^-2 in the Ta-IrO₂ catalyst validates the objective of enhancing performance while significantly reducing the amount of precious metal used. This study provides an effective strategy for the engineered design of high-performance, low-Ir-loading oxygen evolution reaction catalysts through the doping of high-valent metals.

Key words: iridium dioxide, oxygen vacancies, tantalum doping, oxygen evolution reaction (OER), Ir loading