Alloying of ReS2 and VS2 Nanosheets Enhances Electrocatalytic Hydrogen Evolution Reaction

Abstract

AbstractModulating the electronic structure of transition metal dichalcogenides (TMDs) via alloying is challenging despite the additional potential applications. In this study, a solvothermal reaction is used to synthesize composition‐tuned ReS2–VS2 (Re1‐xVxS2) alloy nanosheets featuring an expanded interlayer distance. Increasing x induces a phase transition from the semiconducting 1T″ phase ReS2 to the metallic 3R‐stacking 1T phase VS2. Alloying via homogeneous atomic mixing renders the nanosheets more metallic and with less oxidation than VS2. First‐principles calculations consistently predict the 1T″–1T phase transition of the atomically mixed alloy structures. The calculation also suggests that intercalation drives the 3R stacking of 1T phase VS2. The Re1‐xVxS2 nanosheets at x = 0.3–0.8 exhibit enhanced electrocatalytic activity toward water‐splitting hydrogen evolution reaction (HER) in an acid electrolyte. In situ X‐ray absorption fine structure measurements reveal that the metallicity of the alloys is fully retained during HER. The density of states and Gibbs free energy calculations show that alloying increases the metallicity and thus effectively activates the basal S atoms toward the HER, supporting the observed increased HER performance of the alloy nanosheets.