Switchable Reaction Pathway on RuO ₂ via Atomic Co Doping Toward Oxygen Evolution in Acidic Media

The acidic electrolyte and highly oxidizing environment of proton exchange membrane water electrolysis (PEMWE) pose significant challenges to the stability of Ru-based anode catalysts and limit their practical applications. In this study, Co-doped RuO₂ nanocrystals are synthesized using a one-step annealing method of Co-exchanged Ru-bpydc derivatives. The catalyst demonstrated excellent oxygen evolution reaction (OER) performance, achieving a low overpotential of 205 mV at 10 mA cm^-2 and superior stability, retaining activity for over 1000 h without degradation. Advanced characterization techniques revealed that cobalt doping increases oxygen vacancies and manipulates the reaction pathway by boosting the adsorbate evolution mechanism (AEM) and suppressing the participation of lattice oxygen in OER. Density functional theory (DFT) calculations further confirmed that the electron transfer between Ru and Co site via bridge O in the structure of Ru─O─Co optimized the adsorption energy of oxo-intermediates to promote AEM, thereby boosting stability. In addition, the Co─RuO_x catalyst exhibited good performance as an anode in a PEMWE, demonstrating stable operation for over 100 h at a current density of 100 mA cm^-2. This work presents a viable approach to designing highly active and durable OER catalysts, making significant contributions to the advancement of PEMWE technology.