Mesoporous ATO with Oxygen Vacancies as an Outstanding IrO ₂ Support for Boosting Oxygen Evolution Reaction in PEM Water Electrolysis

This study focuses on the development of high-performance and durable supported iridium-based catalysts. Mesoporous antimony tin oxide (ATO) supports with high conductivity, high specific surface area, and rich in oxygen vacancies is prepared by employing a Pt-catalyzed oxidation of carbon template removal approach. The pore sizes of mesoporous ATO supports are tuned from 5 to 12 nm by adjusting the template removal temperature. These supports, used for IrO₂ substrates, improved ultrahigh OER performance, both catalytic activity and mass transfer, demonstrated excellent Proton exchange membrane water electrolysis (PEMWE) performance with a 0.3 mg cm^-2 of Ir loading, with a polarization performance of 1.75V@2A cm^-2. Simultaneously, the ATO-supported catalysts demonstrated outstanding performance even at ultra-low loadings owning to the ATO mesoporous structure and surface oxygen-vacancy, achieving 1.8V@2A cm^-2 with an Ir loading of 0.05 mg cm^-2. Density functional theory (DFT) computations revealed the strong oxide-support interaction (SOSI) between the IrO₂ and ATO. This research not only validates the effective role of conductive ATO in supported iridium-based catalysts but also provides valuable guidance on the influence of support pore structure to the supported iridium-based catalysts. It offers a new perspective for the development of supported low-iridium OER catalysts.