Dual-Site Cobalt-Doped RuO 2 /TiO 2 Electrocatalyst Enables Stable and Cost-Efficient Acidic Oxygen Evolution for PEM Water Electrolysis

Developing efficient, cost-effective, and durable electrocatalysts for proton exchange membrane water electrolysis (PEMWE) remains a significant challenge, requiring the stabilization and enhancement of catalyst activity under harsh conditions. Here, we present cobalt-doped ruthenium dioxide (Co_0.3Ru_0.7O₂) on TiO₂ as an electrocatalyst toward an acidic oxygen evolution reaction. The Co_0.3Ru_0.7O₂-TiO₂ achieves an impressive overpotential of 322 mV at 1 A cm^-2 and demonstrates stable operation for over 1000 h at 500 mA cm^-2 in a PEMWE device. Comprehensive experimental and theoretical calculation results demonstrate that the doping of Co atoms into the rutile RuO₂ lattice optimizes the geometric configuration. Moreover, the lattice-matched interface between Co_0.3Ru_0.7O₂ and TiO₂ promotes interfacial electron redistribution and stabilizes active centers under oxidative conditions. This facilitates a dual-site fully parallel oxidation (DFO) pathway in which intermediates are synchronously adsorbed and desorbed at Ru and Co sites, enabling direct O-O coupling. This work highlights the synergistic effect of the Ru-Co dual sites and TiO₂ support in establishing a stable, self-regulating electronic environment that drives efficient intermediate transformation via the DFO mechanism.