Dual-Native Vacancy Activated Basal Plane and Conductivity of MoSe2 with High-Efficiency Hydrogen Evolution Reaction.

Although transition metal dichalcogenide MoSe2 is recognized as one of the low-cost and efficient electrocatalysts for the hydrogen evolution reaction (HER), its thermodynamically stable basal plane and semiconducting property still hamper the electrocatalytic activity. Here, it is demonstrated that the basal plane and edges of 2H-MoSe2 toward HER can be activated by introducing dual-native vacancy. The first-principle calculations indicate that both the Se and Mo vacancies together activate the electrocatalytic sites in the basal plane and edges of MoSe2 with the optimal hydrogen adsorption free energy (ΔGH* ) of 0 eV. Experimentally, 2D MoSe2 nanosheet arrays with a large amount of dual-native vacancies are fabricated as a catalytic working electrode, which possesses an overpotential of 126 mV at a current density of 100 mV cm-2 , a Tafel slope of 38 mV dec-1 , and an excellent long-term durability. The findings pave a rational pathway to trigger the activity of inert MoSe2 toward HER and also can be extended to other layered dichalcogenide.