Ru Se@MoS₂ hybrid as a highly efficient electrocatalyst toward hydrogen evolution reaction

Alkaline hydrogen evolution reaction (HER) requires highly efficient and stable catalytic materials, the engineering of which needs overall consideration of the water dissociation process as well as the intermediate hydrogen adsorption process. Herein, a Ru Se@MoS₂ hybrid catalyst was synthesized by the decoration of MoS₂ with Ru Se nanoparticles through a two-step hydrothermal reaction. Due to the bifunctionality mechanism in which Ru promotes the water dissociation and the nearby Se atoms, unsaturated Mo and/or S atoms act as active sites for the intermediate hydrogen adsorption, the hybrid catalyst exhibits an exceptional HER performance in basic media with a rather low overpotential of 45 mV at a current density of 10 mA cm^-2 and a small Tafel slope of 42.9 mV dec^-1. The synergetic effect between Ru Se and MoS₂ not only enables more catalytically active sites, but also increases the inherent conductivity of the hybrid catalyst, leading to more favorable HER kinetics under both alkaline and acidic conditions. As a result, Ru Se@MoS₂ also demonstrates an enhanced catalytic activity toward HER in 0.5 M H₂SO₄ in comparison with pure Ru Se and MoS₂, which requires an overpotential of 120 mV to deliver a 10 mA cm^-2 current density and gives a Tafel slope of 72.2 mV dec^-1. In addition, the hybrid electrocatalyst also exhibits superior electrochemical stability during the long-term HER process in both acidic media and alkaline media.