Phosphorus-Promoted VS ₂ Nanosheets: Unlocking Defect Engineering and Interlayer Modulation for Enhanced Hydrogen Evolution Reaction

VS₂-based catalyst materials have been relatively underexplored for the hydrogen evolution reaction (HER) due to their limited active sites and lower conductivity compared to other transition metal dichalcogenides (TMDCs), despite being cost-effective and stable in alkaline conditions. In this work, we present phosphorus (P)-assisted interlayer expansion and defect engineering of VS₂ nanosheets to significantly enhance their catalytic performance for the HER by improving their intrinsic electronic conductivity. A simple one-pot hydrothermal method is utilized to synthesize P-doped VS₂ nanosheets with a defect-rich, interlayer-expanded structure. Phosphorus doping leads to electron redistribution in the VS₂ system due to differences in the electronegativity. The phosphorus dopant serves as a bridge, helping to more evenly balance the charge gradient between the V and S atoms. The material demonstrates remarkable kinetic activity markers as well as boosted performance toward HER. The synergistically doped P1-VS₂ achieved an overpotential of 191 mV at a current density of 10 mA cm^-2 in a 1 M KOH medium. The catalyst also delivers a low Tafel value of 65.91 mV/dec. Doping of P into the VS₂ lattice changes its physiochemical properties due to the difference in electronegativity between S and P atoms. The intercalated P played a pivotal role in establishing more active sites, which could potentially enhance the HER performance.