Electrocatalytic Activation in ReSe 2 -VSe 2 Alloy Nanosheets to Boost Water-Splitting Hydrogen Evolution Reaction.

It is challenging to control the electronic structure of two-dimensional transition metal dichalcogenides (TMD) for extended applications in renewable energy devices. Here, we synthesized ReSe 2 -VSe 2 (Re 1- x V x Se 2 ) alloy nanosheets over the whole composition range via a colloidal reaction. Increasing x makes the nanosheets more metallic and induces a 1T″-to-1T phase transition at x = 0.5-0.6. Compared to the MoSe 2 -VSe 2 and WSe 2 -VSe 2 alloy nanosheets, ReSe 2 and VSe 2 were mixed more homogeneously at the atomic scale. The alloy nanosheets at x = 0.1-0.7 exhibited an enhanced electrocatalytic activity toward acidic hydrogen evolution reaction (HER). In-situ X-ray absorption fine structure measurements revealed that alloying caused the Re and V atoms to be synergically more active in the HER. Gibbs free energy (ΔG H* ) and density of state calculations confirmed that alloying and Se vacancies effectively activated the metal sites toward HER. The composition dependence of HER performance was explained by homogenous atomic mixing with the increased Se vacancies. Our study provides a strategy for designing new TMD alloy nanosheets with enhanced catalytic activity. This article is protected by copyright. All rights reserved.