Phase-Transition Mo<sub>1-<i>x</i></sub>V<sub><i>x</i></sub>Se<sub>2</sub> Alloy Nanosheets with Rich V-Se Vacancies and Their Enhanced Catalytic Performance of Hydrogen Evolution Reaction.
basic_science · Level V
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- Record sourced from PubMed, PMID 34496215.
- Also identified by DOI 10.1021/acsnano.1c04453.
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Abstract
Alloys of transition-metal dichalcogenide can display distinctive phase evolution because of their two-dimensional structures. Herein, we report the colloidal synthesis of Mo<sub>1-<i>x</i></sub>V<sub><i>x</i></sub>Se<sub>2</sub> alloy nanosheets with full composition tuning. Alloying led to a phase transition at <i>x</i> = 0.7 from the semiconducting 2H phase MoSe<sub>2</sub> to the metallic 1T phase VSe<sub>2</sub>. It also produced significant V and Se vacancies, which became the richest in the 2H phase at <i>x</i> = 0.3-0.5. Extensive spin-polarized density functional theory calculations consistently predicted the 2H-1T phase transition at <i>x</i> = 0.7, in agreement with the experimental results. The vacancy formation energy also supports the formation of V and Se vacancies. Alloying in the 2H phase enhanced the electrocatalytic performance toward hydrogen evolution reaction (HER) at <i>x</i> = 0.3 (in 0.5 M H<sub>2</sub>SO<sub>4</sub>) or 0.4 (in 1 M KOH). The Gibbs free energy along the HER pathway indicates that this maximum performance is due to the highest concentration of active V and Se vacancy sites.