(ReMoV)X ₂ (X = S, Se) Ternary Alloy Nanosheets for Enhanced Electrocatalytic Hydrogen Evolution Reaction

Modulating the electronic structure of 2D transition metal dichalcogenides via alloying can extend their potential applications. In this study, composition-tuned ternary alloy nanosheets of (ReMoV)X₂ (X = S and Se) are synthesized using solvothermal and colloidal reactions, respectively. Ternary alloying occurred with homogeneous atomic mixing over a wide range of compositions (x_V = 0.16-0.80). Compared to (ReV)X₂ binary alloying, ternary alloying produces a more metallic phase with less oxidation. Increasing x_V induces a phase change into a more metallic 1T phase. The (ReMoV)S₂ nanosheets demonstrate enhanced electrocatalytic activity toward the acidic hydrogen evolution reaction (HER) compared to (ReV)S₂. Density functional theory calculations predict that ternary alloying increases the metallicity of the nanosheets. In addition, the Gibbs free energy calculation for hydrogen adsorption (ΔG_H*) shows that ternary alloying effectively activates the basal S atoms for the HER, supporting the enhanced catalytic performance observed experimentally.