Substitutional Vanadium Sulfide Nanodispersed in MoS₂ Film for Pt-Scalable Catalyst

Among transition metal dichalcogenides (TMdCs) as alternatives for Pt-based catalysts, metallic-TMdCs catalysts have highly reactive basal-plane but are unstable. Meanwhile, chemically stable semiconducting-TMdCs show limiting catalytic activity due to their inactive basal-plane. Here, metallic vanadium sulfide (VS_n ) nanodispersed in a semiconducting MoS₂ film (V-MoS₂ ) is proposed as an efficient catalyst. During synthesis, vanadium atoms are substituted into hexagonal monolayer MoS₂ to form randomly distributed VS_n units. The V-MoS₂ film on a Cu electrode exhibits Pt-scalable catalytic performance; current density of 1000 mA cm^-2 at 0.6 V and overpotential of -0.08 V at a current density of 10 mA cm^-2 with excellent cycle stability for hydrogen-evolution-reaction (HER). The high intrinsic HER performance of V-MoS₂ is explained by the efficient electron transfer from the Cu electrode to chalcogen vacancies near vanadium sites with optimal Gibbs free energy (-0.02 eV). This study provides insight into ways to engineer TMdCs at the atomic-level to boost intrinsic catalytic activity for hydrogen evolution.