Dual-Site Cobalt-Doped RuO2/TiO2 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 (Co0.3Ru0.7O2) on TiO2 as an electrocatalyst toward an acidic oxygen evolution reaction. The Co0.3Ru0.7O2-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 Co0.3Ru0.7O2 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.