*typical representative size, areas/dimensions may vary
||~ 1.4 eV (indirect)
||Vanadium selenide, Bis(selanylidene)vanadium
|Classification / Family
Transition metal dichalcogenides (TMDCs), 2D Semiconductor materials, Charge Density Wave (CDW), Hydrogen Revolution Reactions (HER), Nano-electronics, Nano-photonics, Photovoltaic, Materials science
||Synthetic - Chemical Vapour Transport (CVT)
||Dark brown crystal
Vanadium diselenide (VSe2) is a Group V transition metal dichalcogenide (TMDC). Single-layer VSe2 film consists of stacks of one layer of hexagonally close-packed transition metal vanadium atoms sandwiched between two layers of chalcogen selenium atoms in the sequence of Se–V–Se. The metal atoms are octahedrally coordinated and covalently bonded to the chalcogen atoms. The layers are stacked together by van der Waals (vdW) forces. Like black phosphorus and MoSe2, these can be exfoliated into 2D thin layers.
In nature, VSe2 exists only in 1T as its thermodynamically-stable phase (space group: P63mc). Bulk 1T-VSe2 is a metal and shows unique three-dimensional (3D) CDW properties below 110K. Evidence shows that there is a thickness dependence of the CDW transition temperature (Tp) in VSe2, which means that the CDW collective state is significantly modulated by the thickness of the flake.
The metallic properties of vanadium diselenide contribute to its potential for applications in supercapacitors and lithium-ion batteries such as electrodes, moisture-detection sensors, and electrocatalysts for hydrogen revolution reactions (HER).
Vanadium diselenide is manufactured using chemical vapour transport (CVT) crystallisation, with crystals having a purity in excess of 99.999%.
Vanadium diselenide single crystals can be used to prepare monolayer and few-layer VSe2 by mechanical or liquid exfoliation.
Literature and Reviews
Field-Effect Tuned Adsorption Dynamics of VSe2 Nanosheets for Enhanced Hydrogen Evolution Reaction, M. Yan et al., Nano Lett. 2017, 17, 4109−4115 (2017); DOI: 10.1021/acs.nanolett.7b00855.
Electronic Structure and Enhanced Charge-Density Wave Order of Monolayer VSe2, J. Feng et al., Nano Lett., 18, 4493−4499 (2018); DOI: 10.1021/acs.nanolett.8b01649.
Emergence of a Metal−Insulator Transition and High-Temperature Charge-Density Waves in VSe2 at the Monolayer Limit, G, Duvjir et al., Nano Lett. 2018, 18, 5432−5438 (2018); DOI: 10.1021/acs.nanolett.8b01764.
Chemical Vapor Deposition of 2D Vanadium Disulfide and Diselenide and Raman Characterization of the Phase Transitions, M. Hossain et al, Adv. Mater. Interfaces, 5, 1800528 (2018); DOI: 10.1002/admi.201800528.
Versatile Electronic Properties of VSe2 Bulk, Few-Layers, Monolayer, Nanoribbons, and Nanotubes: A Computational Exploration, F. Li et al., J. Phys. Chem. C, 118, 21264−21274 (2014); doi: 10.1021/jp507093t.