Enhanced Electrocatalytic Hydrogen Evolution Activity in Single-Atom Pt-Decorated VS₂ Nanosheets

Enhancing catalytic activity by decorating noble metals in catalysts provides an opportunity for promoting the electrocatalytic hydrogen evolution reaction (HER) application. However, there are few systematic studies on regulating the structures of noble metals in catalytic materials and investigating their influence on HER. Herein, Pt catalysts with different structures including single atoms (SAs), clusters, and nanoparticles well-controllably anchored on VS₂ nanosheets through a cost-effective optothermal method are reported, and their HER performance is studied. The most efficient Pt-decorated VS₂ catalyst (with both Pt SAs and clusters) delivers an overpotential of 77 mV at 10 mA cm^-2, close to that of Pt/C (48 mV). However, the optimal mass activity of Pt (normalizing to Pt content) is obtained from only SA Pt-decorated VS₂ (i.e., 22.88 A mg_Pt^-1 at 200 mV) and is 12 times greater than that of the Pt/C (1.87 A mg_Pt^-1), attributed to the greatly enhanced Pt utilization. Additionally, the theoretical simulations reveal that Pt SA decoration makes the adsorption free energy of H* closer to the thermoneutral value and improves the charge-transfer kinetics, significantly enhancing HER activity. This work offers a pathway to prepare the desired catalyst based on synergy of Pt structures and VS₂ and reveals the intrinsic mechanism for enhancing catalytic activity, which is important for HER applications.