Stability of Multivalent Ruthenium on CoWO4 Nanosheets for Improved Electrochemical Water Splitting with Alkaline Electrolyte.

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.