Inhibiting overoxidation of ruthenium oxides by zinc doping for promoting a highly efficient proton exchange membrane water electrolyzer

For proton exchange membrane water electrolyzers (PEMWE), it is critical to develop durable and powerful anodic oxygen evolution reaction (OER) catalysts. For acidic OER in PEMWE, efficient zinc-doped ruthenium dioxide catalysts with abundant oxygen vacancies and stable Ru–O bonding are fabricated here. The optimal Zn0.1Ru0.9O2−x requires only 212 mV overpotential at a current density of 10 mA cm−2 and maintains stability for over 500 h, with a degradation rate of only 30 μV h−1 at 10 mA cm−2. When used as the anode of a practical PEMWE device, Zn0.1Ru0.9O2−x enables over 100 h of long-term stability at 100 mA cm−2. DFT calculations reveal that Zn0.1Ru0.9O2−x, containing oxygen vacancies, exhibits a lowered d-band center energy, which enhances the adsorption and desorption of oxygen intermediates, thereby improving OER activity. Experimental and theoretical studies show that Zn doping in RuO2 enhances Ru–O bonding and increases oxygen vacancies. The synergy of Zn dopant and Ru species effectively stabilizes Ru–O bonding and prevents Ru species from overoxidizing during the OER process. Therefore, the modulated electronic structure of RuO2 with Zn doping accelerates OER kinetics and promotes the durability of Ru–O bonding. This work develops a viable strategy for attaining favorable kinetics and durable oxygen evolution within energy conversion devices.