Self-Catalyzed Ru Redeposition Based on Co, Zn-Driven Double Anchoring for Robust Acidic Water Oxidation

The redeposition of high-valence Run>4+ at oxidation potential is slower than its dissolution due to weak electronic interactions with substrates, limiting water oxidation performance. We propose a novel self-catalyzed redeposition strategy fuelled by Co and Zn codoping to establish a new dissolution–redeposition balance of Ru. Co, Zn-doped RuO2 with unique double anchoring effect is prepared, where electron-donating Co and Zn reduce Run>4+ leaching by inhibiting overoxidation and shortening Ru–O bonds (first anchoring). More importantly, Run>4+ is rapidly and stably deposited as active Ru(OH)62– through Co2+/Co3+ redox-driven self-catalysis (second anchoring). Regulating the Co content can modulate the self-catalysis strength, thus stabilizing dissolution–redeposition equilibrium via directional electron flow from Co to Ru. The redeposited Co0.2Zn0.8@RuO2 presents shortened Ru–O bonds and abundant defects, displaying ultralow overpotential at 10 mA·cm–2 (150 mV), surpassing the RuO2 benchmark and most catalysts. Furthermore, Co0.2Zn0.8@RuO2 exhibits excellent stability at 500 mA·cm–2 for 100 h. This self-catalyzed redeposition offers a new routine to break the activity–stability trade-off of electrocatalysts, especially in membrane water electrolyzers.