Strong Catalyst‐Support Interaction Stabilizes IrO _x Nanoclusters for Efficient Acidic Oxygen Evolution

Abstract Low‐loading iridium (Ir) catalysts hold great promise for the acidic oxygen evolution reaction (OER) due to their typically high Ir utilization and reduced cost. However, their practical application is limited by poor stability under the harsh acidic oxidative conditions of proton exchange membrane (PEM) water electrolysis. Here, a controlled structural transformation strategy is presented that converts an unstable LiCoO 2 ‐supported Ir single‐atom catalyst (Ir‐LiCoO 2 ) into a corrosion‐resistant Co 3 O 4 ‐supported IrO x nanocluster catalyst (IrO x /Co 3 O 4 ), significantly enhancing catalyst durability. Strong catalyst‐support interactions between IrO x and Co 3 O 4 facilitate charge transfer, thereby stabilizing the IrO x nanoclusters against leaching and optimizing the electronic structure of the Ir active sites. As a result, IrO x /Co 3 O 4 exhibits substantially enhanced OER performance compared to Ir‐LiCoO 2 , achieving excellent operational stability over 1200 h and a low overpotential of ≈233 mV at 10 mA cm −2 in 0.5 m H 2 SO 4 . This superior performance is further validated in PEM electrolyzers, confirming its practical applicability. Furthermore, theoretical calculations reveal that Ir sites in IrO x /Co 3 O 4 exhibit higher dissolution potentials and improve charge transfer capabilities with OER intermediates compare to those in Ir‐LiCoO 2 and IrO 2 , which effectively suppresses Ir leaching and lowers the energy barrier of the potential‐determining step.