Porous Antimony Tin Oxide with a Particle Assembly Structure as an IrO₂ Support for an Efficient Oxygen Evolution Reaction in Proton-Exchange Membrane Water Electrolysis

Proton-exchange membrane water electrolysis (PEMWE) holds great promise for hydrogen production applications. However, the reliance of PEMWE membrane electrodes on high loadings of expensive iridium poses a significant barrier to their commercial viability. Therefore, the development of high-performance oxygen evolution catalysts with a low iridium content is of critical importance. In this research, a porous antimony tin oxide (ATO) conductive support with a particle assembly aggregate structure was fabricated by a carbon template removal method. ATO-supported IrO₂ exhibits significantly improved oxygen evolution reaction (OER) activity, with a much lower overpotential compared to the unsupported IrO₂ catalyst. Moreover, it achieves 1.8 V at 2 A cm^-2 with an ultralow loading of iridium (0.3 mg_Ir cm^-2) for the proton-exchange membrane electrolyzer. Characterization techniques and density functional theory calculations have elucidated that the enhanced performance is attributed to the porous morphology of ATO and the strong metal oxide-support interaction between IrO₂ and the ATO support. These findings validate the practicality of conductive nanostructured antimony-tin-oxide-supported catalysts for PEMWE applications and offer a pathway for the design of low-Ir OER catalysts.