Supported Ir-based anode catalysts for proton exchange membrane water electrolysis: recent progress and perspectives

Proton exchange membrane water electrolysis (PEMWE) is a promising green technology for hydrogen production. It enables operation at high current densities, rapid dynamic response, and the generation of high-purity hydrogen. However, the large-scale commercialization of this technology is constrained by the scarcity and high cost of iridium (Ir) which is a rare metal that serves as the most reliable anode catalyst for the acidic oxygen evolution reaction (OER). Consequently, supported iridium-based catalysts have been proposed as a crucial strategy to reduce iridium loading while simultaneously maintaining catalytic activity and durability. Dispersing iridium species onto suitable support materials not only enhances iridium utilization efficiency but also effectively modulates the local coordination environment, electronic structure, and interfacial stability of the active sites. This mini-review compares TiO₂-, SnO₂-, and other oxide-supported Ir catalysts through four linked questions: how the support controls Ir dispersion and working-state structure; how conductivity and corrosion resistance constrain catalyst-layer construction; how support chemistry affects activity and dissolution; and whether half-cell gains are retained in low-Ir membrane electrode assemblies. The resulting framework highlights the dispersion-stability trade-off, support degradation, and incomplete translation from model electrodes to practical devices.