Inter-doped ruthenium–nickel oxide heterostructure nanosheets with dual active centers for electrochemical-/solar-driven overall water splitting

Rational design and synthesis of transition-metal-oxides-based bifunctional catalysts with excellent activity and stability remain a challenge for efficient water splitting. Herein, integrating the active components of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) into novel inter-doped ruthenium-nickel oxide [(Ru-Ni)Ox] heterostructure by self-templated strategy is proposed. The (Ru-Ni)Ox electrode exhibits superb HER and OER activities with minimum overpotentials of 14.5 mV and 237.2 mV to afford 10 mA cm−2, respectively. According, a voltage of 1.48 V is required to drive 10 mA cm−2 for overall water-alkali splitting. The combined spectroscopy analysis and theory calculations reveal electronic structure regulation and potential-induced synergy, the modulation of the d-band center optimizes the adsorption energy of H* for enhanced HER on Ru-NiO, and NiO-derived NiOOH favors H2O dissociation for enhanced OER on Ni-RuO2. The successful assembly of a solar-driven alkaline electrolyzer provides more flexibility applications of (Ru-Ni)Ox electrocatalyst.