Breaking the Activity‐Stability Trade‐Off of RuO 2 via Metallic Ru Bilateral Regulation for Acidic Oxygen Evolution Reaction

Developing highly efficient acidic oxygen evolution reaction (OER) electrocatalysts is crucial for proton exchange membrane water electrolyzer. RuO2 electrocatalysts, which followed a kinetically favorable lattice oxygen mechanism, perform a preferable intrinsic activity, but poor stability for acidic OER. Recent work often sacrifices the intrinsic activity of RuO2 to enhance stability. The balance between the activity and stability of RuO2-based catalysts is still overlooked in current research. Here, we report a controlled method to introduce metallic Ru onto RuO2 catalysts to form the Ru4+─O─Ru0 interfacial structure for decreasing the Ru4+ oxidation state and promoting deprotonation kinetics. Metallic Ru can serve as the electron donor to lower the oxidation state of *Vo-RuO4 2- in Ru/RuO2 for stabilizing the structure of *Vo-RuO4 2--Ru/RuO2 to favour the acidic OER stability. Moreover, the deprotonation kinetics via the interfacial oxygen site between Ru4+ and Ru0 is significantly enhanced on Ru/RuO2 catalysts to improve the acidic OER activity. This work offers a unique perspective to balance the acidic OER activity and stability of RuO2.