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

Abstract 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 IrO ₂ 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 IrO ₂ 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.