Synergistic Engineering of Dopant and Support of Ru Oxide Catalyst Enables Ultrahigh Performance for Acidic Oxygen Evolution

Abstract Active and robust electrocatalysts for acidic oxygen evolution reaction (OER) are of crucial importance for efficient proton exchange membrane water electrolyzer (PEM‐WE). Ruthenium (Ru) oxide has attracted considerable attention due to its high activity. However, the unsatisfying stability of Ru oxide in acidic OER environments hinders the application. Here, Ce‐doped RuO 2 nanoparticles are designed and supported on Co─N─C material (Ce@RuO 2 /CoNC) for acidic OER. It is demonstrated that Ce@RuO 2 /CoNC delivers a super low overpotential of 150 mV and an excellent stability of 1000 h at 10 mA cm −2 , outperforming most previously reported Ru‐based catalysts. The mass activity is estimated as 2365.5 Ag Ru −1 at 1.5 V (vs RHE), representing ≈2× advance compared to the best prior study. Furthermore, applied in a single‐cell PEM‐WE device, it can steadily operate for 1000 h at 200 mA cm −2 . The studies show that Ce‐doping and Co─N─C support synergistically enhance the activity and stability of Ru oxide by optimizing the free energies of OER intermediates and suppressing the dissolution of Ru.