Hierarchical nanostructure of Ru ions strongly coupled with CoWO₄ nanosheet nanoarrays was synthesized by a simple co-precipitation and solvothermal methods. When used as both an anodic and a cathodic electrocatalyst, the Ru₂(M)−CoWO₄/CC couple showed outstanding overall water splitting performance with a cell voltage of 1.48 V@ 10 mA cm⁻².

Abstract

Engineering low-cost electrocatalysts with desired features is vital to decrease the energy consumption but challenging for superior water splitting. Herein, we development a facile strategy by the addition of multivalence ruthenium (Ru) into the CoWO₄/CC system. During the synthesis process, the most of Ru³⁺ ions were insinuated into the lattice of CoWO₄, while the residual Ru³⁺ ions were reduced to metallic Ru and further attached to the interface between carbon cloth and CoWO₄ sheets. The optimal Ru₂(M)−CoWO₄/CC exhibited superior performance for the HER with an overpotential of 85 mV@10 mA cm⁻², which was much better than most of reported electrocatalysts, regarding OER, a low overpotential of 240 mV@10 mA cm⁻² was sufficient. In comparison to Ru₂(0)−CoWO₄/CC with the same Ru mass loading, multivalence Ru₂(M)−CoWO₄/CC required a lower overpotential for OER and HER, respectively. The Ru₂(M)−CoWO₄/CC couple showed excellent overall water splitting performance at a cell voltage of 1.48 V@10 mA cm⁻² for used as both anodic and cathodic electrocatalysts. Results of the study showed that the electrocatalytic activity of Ru₂(M)−CoWO₄/CC was attributed to the in-situ transformation of Ru/Co sites, the multivalent Ru ions and the synergistic effect of different metal species stimulated the intrinsic activity of CoWO₄/CC.