Developing the transition metal dichalcogenides (TMD) alloyed nanostructure is a challenging subject to extend the applications in renewable energy devices. Here, we synthesized ReSe₂-VSe₂ (Re_1-xV_xSe₂) alloy nanosheets at whole compositions via a colloidal reaction. Increasing x makes the nanosheets more metallic and induces a sequential 1T″-1T phase transition (x = 0.6). Compared to MoSe₂-VSe₂ and WSe₂-VSe₂, ReSe₂-VSe₂ exhibits more random mixing of metal atoms. The alloys at x = 0.1-0.7 exhibit an enhanced electrocatalytic activity toward acidic hydrogen evolution reaction (HER), which was ascribed to effective atomic mixing with the Se vacancies. Operando X-ray absorption spectroscopy revealed that the Re and Se atoms become more HER active upon the alloying. The first-principles calculation consistently predicted the composition-dependent crystal structures. Gibbs free energy (△G_H*) calculation verified that the alloying effectively activates the H adsorption on the Re and Se sites. Our study provides a strategy for designing new TMD alloy nanosheets for enhanced catalytic activity.

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Figure 1. SEM and HRTEM images of Re<sub>1-</sub><i><sub>x</sub></i>V<i><sub>x</sub></i>Se<sub>2</sub> nanosheets.

Figure 1. SEM and HRTEM images of Re_1-_xV_xSe₂ nanosheets.

Ik Seon Kwon

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