Ru-incorporated oxygen-vacancy-enriched MoO2 electrocatalysts for hydrogen evolution reaction

Designing highly efficient Pt-free electrocatalysts with low overpotential for the alkaline hydrogen evolution reaction (HER) remains a significant challenge. In this paper, we successfully construct Ru-incorporated oxygen-vacancy-enriched MoO2 nanosheets (Ru/MoO2−x) for the HER through a “one stone two birds” strategy. This strategy can solve two urgent problems simultaneously, the intrinsic electrochemical activity of original MoO2 is far from satisfactory and the H2O adsorption/dissociation abilities of Ru are weak. Specifically, the oxygen-vacancy-enriched MoO3 serves as an excellent platform for anchoring and trapping Ru ions. In-depth analyses indicate that the incorporation of Ru nanoclusters induces transition from MoO3 to MoO2, generates oxygen vacancies, and creates Ru-O-Mo sites. The synergistic effect of Ru nanoclusters, Ru-O-Mo sites and oxygen-vacancy-enriched MoO2 will endow the obtained catalyst excellent electrocatalytic activity. In particular, the optimal Ru/MoO2−x electrocatalyst delivered a low overpotential of 29 mV at 10 mA cm−2 in a basic electrolyte.