Polytypic Phase Transition of Nb<sub>1-<i>x</i></sub>V<sub><i>x</i></sub>Se<sub>2</sub> via Colloidal Synthesis and Their Catalytic Activity toward Hydrogen Evolution Reaction.
basic_science · Level V
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- Record sourced from PubMed, PMID 35245026.
- Also identified by DOI 10.1021/acsnano.1c10301.
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Abstract
Polytypes of two-dimensional transition metal dichalcogenide can extend the architecture and application of nanostructures. Herein, Nb<sub>1-<i>x</i></sub>V<sub><i>x</i></sub>Se<sub>2</sub> alloy nanosheets in the full composition range (<i>x</i>) were synthesized by a colloidal reaction. At <i>x</i> = 0.1-0.3, a phase transition occurred from various hexagonal (three 2H and one 4H types) phase NbSe<sub>2</sub> to an atomically homogeneous 1T phase VSe<sub>2</sub>. Density functional theory calculations also revealed a polytypic phase transition at <i>x</i> = 0.3, which was shifted close to 0 in the presence of Se vacancies. Furthermore, the calculations validate favorable formation of Se vacancies at the phase transition. The sample at <i>x</i> = 0.3 exhibited enhanced electrocatalytic activity toward the hydrogen evolution reaction (HER) in 0.5 M H<sub>2</sub>SO<sub>4</sub>. The Gibbs free energy indicates that the catalytic HER performance is correlated with the active Se vacancy sites of polytypic structures.