Journal Article

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+& horbar;O & horbar;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-RuO42- in Ru/RuO2 for stabilizing the structure of *Vo-RuO42--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.