Electronic structure regulation of ruthenium sites via cobalt and copper dual doping for acidic water splitting

Ruthenium-based materials are widely regarded as promising electrocatalysts for water splitting, owing to their platinum-like electronic characteristics and favorable binding energies with reaction intermediates. Nevertheless, the oxidation behavior of ruthenium at elevated potentials induces structural degradation, precipitating the dissolution of active species and thereby undermining stability during the oxygen evolution reaction (OER) in acidic media. Herein, we reported a novel RuO₂@Ru heterostructured catalyst with cobalt and copper co-doping (Co, Cu-RuO₂@Ru) for stable acidic water electrolysis. The heterostructured catalyst exhibited exceptional performance, attaining an ultralow overpotential of 182 mV at 10 mA cm^-2 for the OER and a low overpotential of 217 mV at 250 mA cm^-2 for the hydrogen evolution reaction (HER), surpassing the benchmark Pt/C catalyst. Electronic-structure analyses indicated that the RuO₂@Ru heterointerface promoted charge redistribution following Co and Cu co-doping, effectively reducing the oxidation state of ruthenium within RuO₂ and yielding an electron-deficient metallic Ru phase. Moreover, mechanistic investigations revealed that electron transfer induced by Co and Cu co-doping optimizes the adsorption and desorption kinetics of hydrogen and oxygenated intermediates, thereby accelerating the reaction kinetics of both HER and OER in acidic media, ultimately leading to exceptional overall water splitting performance.