Nickel-decorated RuO₂ nanocrystals with rich oxygen vacancies for high-efficiency overall water splitting

Designing transition metal-oxide-based bifunctional electrocatalysts with excellent activity and stability for OER/HER to achieve efficient water splitting is of great importance for renewable energy technologies. Herein, a highly efficient bifunctional catalysts with oxygen-rich vacancies of nickel-decorated RuO₂ (NiRuO_2-x) prepared by a unique one-pot glucose-blowing approach were investigated. Remarkably, the NiRuO_2-x catalysts exhibited excellent HER and OER activity at 10 mA cm^-2 in alkaline solution with only a minimum overpotential of 51 mV and 245 mV, respectively. Furthermore, the NiRuO_2-x overall water splitting exhibited an ultra-low voltage of 1.6 V to obtain 10 mA cm^-2 and stability for more than 10 h. XPS measurement and theoretical calculations demonstrated that the introduction of Ni-dopant and oxygen vacancies make the d-band center to lie close to the Fermi energy level, the chemical bonds between the active site and the adsorbed oxygen intermediate state are enhanced, thereby lowering the reaction activation barriers of HER and OER. The assembly of solar-driven alkaline electrolyzers facilitate the application of the NiRuO_2-x bifunctional catalysts.