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 *V_o-RuO₄ ^2- in Ru/RuO₂ for stabilizing the structure of *V_o-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.