Constrained Minimal Interface on Iridium Oxide Surfaces for Acidic Water Oxidation with Low Iridium Loading

Iridium-based oxides are the best commercial catalysts for the acidic oxygen evolution reaction (OER) because of their relatively excellent stability. However, their high price and low OER activity have greatly impeded their commercialization. Doping IrO₂ with transition metals significantly enhances its activity; however, the instability of transition metals in OER kinetic processes can result in substantial metal dissolution and ion exchange. Herein, we report a metastable amorphous Fe:IrO₂ OER catalyst, which provided excellent structural flexibility, enhancing the catalyst's performance in the OER with minimal Ir loading. Their constrained minimal interface structure ensures stability, as shown by the minimal dissolution of Fe ions after chronopotentiometry tests. In situ FTIR and DEMS analyses reveal that the catalyst utilizes an *O-*O radical coupling mechanism to generate O₂. These findings illustrate the important role of metastable amorphous IrO₂ catalysts in establishing an optimal catalytic pathway for stable and excellent electrochemical properties.