(495h) Investigation of Supported Catalysts for Oxygen Evolution Reaction Toward the Low Ir Anode in Polymer Electrolyte Membrane Water Electrode

With the gravity of climate change and environmental pollution, the need for large-scale renewable energy production for carbon neutrality is becoming urgent. This urgency has driven the expansion of solar and wind energy installations, along with the parallel development of technologies to convert intermittent power into storable and transportable hydrogen fuel. Among these technologies, proton exchange membrane water electrolysis (PEMWE) has emerged as a promising route for producing high-purity green hydrogen with rapid system response and high energy efficiency. However, the high cost and scarcity of iridium (Ir) used as the oxygen evolution reaction (OER) catalyst remain significant barriers to scaling up PEMWE systems. To maintain high electrochemical performance while reducing Ir content, dispersing Ir on conductive and stable supports has become one of the most effective strategies.

This presentation mainly introduces an approach using a supported OER catalyst, which is composed of Ir nanoparticles uniformly dispersed on hierarchical multi-porous tantalum oxide (M–Ta₂O₅) structures having both mesopores and macropores. The M–Ta₂O₅ support was synthesized via a sacrificial polystyrene templating method, allowing controlled pore architecture without hazardous post-processing. Iridium nanostructures were formed on the support using a formic acid reduction method, promoting enhanced Ir dispersion and electron transfer. The catalyst demonstrated excellent OER activity and Ir utilization, enabling single-cell PEMWE operation at 2.5 A/cm² and 1.89 V with a low Ir loading of 0.2 mg/cm². Compared to conventional IrO₂, the Ir/M–Ta₂O₅ catalyst significantly improved mass activity and reduced ohmic and charge transfer resistances, which are suggested by the distribution of relaxation time analysis of the catalyst layer. In addition, I would like to discuss the possibility of expanding our approach for low Ir anode using new meal oxide support such as MnO₂ and WO₃. This presentation will provide the effectiveness of porous oxide supports in boosting performance and reducing precious metal usage in PEMWE systems.