An Up-Scalable Solid-State Approach to Synthesize Iridium Nanoparticles on ATO for Water Splitting

Proton exchange membrane water electrolysis (PEMWE) technology commercialization strongly relies on developing efficient and cost-effective anode catalysts. One key challenge is the high cost associated with IrO₂, which can be mitigated by reducing iridium (Ir) loading. A promising approach to achieving this is using a conductive support material to anchor Ir/IrO₂. In this study, we explored depositing metallic Ir on antimony-doped tin oxide (ATO) using a solid-state method. This approach is straightforward and time-efficient. Among four samples with 50 wt % Ir loading, one prepared with NaOH in 100% ethanol (Ir/ATO-NE) exhibited the highest specific oxygen evolution reaction (OER) performance. The Ir/ATO-NE catalyst achieved 340 A g_Ir^-1 at 1.6 V (versus RHE), surpassing a commercial IrO₂ catalyst, which showed 282 A g_Ir^-1. Additionally, Ir/ATO-NE demonstrated the lowest Tafel slope, indicating enhanced oxygen evolution kinetics and long-term durability comparable to commercial catalysts. Electron microscopy revealed uniform Ir nanoparticle (NP) sizes and a complete layer of Ir NPs on the support, in contrast to other samples. This study introduces a synthesis protocol for Ir catalysts that is efficient, simple, and effective for oxygen evolution in acidic media.