An insight into the enhanced mechanism of Ru–MoO₂ interfacial chemical bonding for hydrogen evolution reaction in alkaline media

An effective strategy was proposed to control the formation of the interfacial bonding between Ru and molybdenum oxide support to stabilize the Ru atoms with the aim to enhance the hydrogen evolution reaction (HER) activity of the resultant catalysts in alkaline medium. The different interfacial chemical bonds, including Ru–O, Ru–O–Mo, and mixed Ru–Mo/Ru–O–Mo, were prepared using an induced activation strategy by controlling the composition of reducing agents in the calcination process. And the regulation mechanism of the interfacial chemical bonds in molybdenum oxide supported Ru catalysts for optimizing HER activity was investigated by density functional theory (DFT) and experimental studies. We found that a controlled interfacial chemical Ru–O–Mo bonding in Ru-MoO₂/C manifests a 12-fold activity increase in catalyzing the hydrogen evolution reaction relative to the conventional metal/metal oxide catalyst (Ru-O-MoO₂/C). In a bifunctional effect, the interfacial chemical Ru-O-Mo sites promoted the dissociation of water and the production of hydrogen intermediates that were then adsorbed on the nearby Ru surfaces and recombined into molecular hydrogen. As compared, the nearby Ru surfaces in Ru–Mo bonding have weak adsorption capacity for the generation of these hydrogen intermediates, resulting in a 5-fold increase HER activity for Ru-Mo-MoO₂/C catalyst compared with Ru-O-MoO₂/C.