Modulating Crystallinity and Surface Electronic Structure of IrO₂ via Gadolinium Doping to Promote Acidic Oxygen Evolution

Simultaneously improving the activity and long-term stability of the oxygen evolution electrocatalysts in acidic media is an ever ongoing process for the water electrolysis technique. Here, we report a novel Gd-doped porous IrO 2 (Gd-pIrO 2 ) catalyst with a high specific surface at 293 m 2 g –1 and enhanced catalytic activity toward oxygen evolution reaction (OER), where the overpotential required to reach 10 mA cm –2 is only 287 mV. We found that Gd 3+ doping induces the formation of abundant oxygen vacancies and an increase in Ir 4+ /Ir 3+ ratio, due to the charge compensating mechanism in defect chemistry. Combining experimental techniques and density functional theory calculations, we revealed that Gd doping at an appropriate content leads to an overall enhancement in OER performance, where oxygen vacancies facilitate the adsorption of water molecules and the high ratio of Ir 4+ /Ir 3+ facilitates the H dissociation. The novel strategy proposed in this study provides an efficient way for designing high-performance electrocatalysts for water electrolysis.