Local Coordination Asymmetry Engineering Activates Oxide Path Mechanism in Dopant‐Free RuO 2 for Ultra‐Durable Acidic Water Oxidation

ABSTRACT Developing ruthenium‐based anode electrocatalysts to replace commercial iridium is crucial for reducing the cost of proton exchange membrane (PEM) water electrolysis. However, conventional RuO 2 suffers from limited long‐term stability and severe overoxidation drawbacks. Herein, we employ dynamic H 2 bubble template (DHBT)‐assisted electrodeposition combined with calcination to fabricate disorderly connected regular/irregular Ru‐O 6 octahedra. In situ experiments and theoretical calculations reveal that this local coordination asymmetry favors an oxide path mechanism (OPM) involving direct O‐O coupling while suppressing *OOH formation and substantial lattice‐oxygen participation. The optimized d‐RuO 2‐x catalyst requires an overpotential of only 154 mV to reach 10 mA cm −2 and maintains stable operation for over 3200 h at this current density. Crucially, in a PEM water electrolyzer, the catalyst operates robustly for over 2100 h at 200 mA cm −2 under continuous and start‐shutdown conditions. These results demonstrate that local coordination asymmetry engineering can tune OER pathway selection in dopant‐free RuO 2 ‐based catalysts and provide a promising route toward durable acidic OER anodes.