Solid-State Synthesis of Efficient Supported Iridium Catalysts for the Acidic Oxygen Evolution Reaction

Abstract

Proton-exchange membrane (PEM) water electrolysis is a key technology for green hydrogen production, offering distinct advantages such as compatibility with intermittent renewable energy sources. However, its large-scale deployment remains hindered by the lack of abundant and cost-effective catalysts for the acidic oxygen evolution reaction (OER). At present, Ir-based materials are the only viable type of catalyst with sufficient activity and stability under industrial operating condi-tions. While significant recent advances in Ir recycling have helped reduce concerns about availability and cost, achieving scalable and rapid synthesis of high-performance Ir catalysts remains a major challenge. Here, we present a solid-state syn-thesis method for producing highly active and durable supported Ir catalysts for acidic OER. Under OER conditions, the as-synthesized supported Ir nanoparticles transform into Ir-IrOx core–shell structures with partially or fully oxidized surfaces that exhibit excellent performance as demonstrated by reproducible electrochemical tests, delivering three-fold higher mass-specific activity (174 mA mgIr⁻¹ at 1.55 V vs. RHE), more than ninefold higher surface-specific activity (1295 mA C⁻¹ at 1.55 V vs. RHE), and enhanced stability (retaining 83% of the mass-specific activity and 92% of the surface-specific activi-ty after stress tests) compared with a benchmark IrO2 catalyst. The structural robustness of the Ir-IrOx configuration during acidic OER was validated through a range of ex-situ and in-situ characterization techniques. This synthesis approach and the resulting catalyst architecture provide valuable guidance for the rational design of advanced materials to enable sus-tainable green hydrogen production.