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

Abstract

The redeposition of high-valence Ru^n>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 Ru^n>4+ leaching by inhibiting overoxidation and shortening Ru–O bonds (first anchoring). More importantly, Ru^n>4+ is rapidly and stably deposited as active Ru(OH)₆^2– 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 Co_0.2Zn_0.8@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, Co_0.2Zn_0.8@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.