Self-Coordinating Electronic Metal–Support Interaction Stabilizes Ultralow-Loading Ir Single Atoms for Durable Acidic Oxygen Evolution

Engineering electronic metal–support interactions (EMSI) enables scalable proton exchange membrane water electrolysis (PEMWE) at ultralow Ir loadings by buffering Ir against overoxidation and dissolution under acidic oxygen evolution conditions (OER). However, a seemingly disparate interpretation has persisted: high-valent Ir is often associated with optimal intermediate adsorption, whereas low-valent Ir correlates with improved corrosion resistance, suggesting that static EMSI fails to rationalize the activity-stability trade-off. Here, we construct an atomically dispersed Ir–O–Co interface by anchoring isolated Ir single atoms on spinel Co 3 O 4, providing a new perspective on a dynamic charge-compensation mechanism: at low bias, the Ir site is progressively oxidized to enhance water activation and intermediate turnover; at high bias, the Co 3 O 4 compensates charge back to the Ir site, thereby suppressing overoxidation-driven dissolution. Such self-coordinating EMSI breaks the conventional activity-stability trade-off in acidic OER. In an integrated PEM electrolyzer, the Ir single-atom catalyst sustains operation for >1500 h at 1.0 A cm –2 with an ultralow Ir loading of 0.1 mg cm –2, highlighting the importance of self-coordinating EMSI for durable, precious-metal-minimized PEMWE anodes.