Novel single-layer vanadium sulphide phases

Abstract

VS 2 is a challenging material to prepare stoichiometrically in the bulk, and the single layer has not been successfully isolated before now. Here we report the first realization of single-layer VS 2 , which we have prepared epitaxially with high quality on Au(111) in the octahedral (1T) structure. We find that we can deplete the VS 2 lattice of S by annealing in vacuum so as to create an entirely new twodimensional compound that has no bulk analogue. The transition is reversible upon annealing in an H 2 S gas atmosphere. We report the structural properties of both the stoichiometric and S-depleted compounds on the basis of low-energy electron diffraction, X-ray photoelectron spectroscopy and diffraction, and scanning tunneling microscopy experiments.

Accurate Control of VS2 Nanosheets for Coexisting High Photoluminescence and Photothermal Conversion Efficiency

“…Layered bulk VS 2 is thermodynamically unstable polymorph and tending to exist in S‐deficient forms . In a typical preparation process, oxygen can be introduced in the supercritical fluid by an initial ultrasonic process.…”

Accurate Control of VS2 Nanosheets for Coexisting High Photoluminescence and Photothermal Conversion Efficiency

“…Layered bulk VS 2 is thermodynamically unstable polymorph and tending to exist in S-deficient forms. [23] In atypical preparation process,o xygen can be introduced in the supercritical fluid by an initial ultrasonic process.T herefore,V S 2 can be kinetically and thermodynamically oxidized to VO 2 at raised temperature (80 8 8C) and high pressure.A nd this phenomenon was consistent with our previous researches on the transition of WS 2 to WO 3 [24] and MoS 2 to MoO 3 [17] at 80 8 8C. Meanwhile,recent investigations demonstrate that the deformation and strain engineering can contribute to the reversible amorphous-to-crystalline transition, and atoms can be rearranged under exterior stress-driving to form crystal.…”

Molecular Nanowire Bonding to Epitaxial Single‐Layer MoS2 by an On‐Surface Ullmann Coupling Reaction

“…Our results provide an interesting route to fabricate hybrid systems of organic molecules and 2D materials on Au surfaces, but the method needs to be developed for application on oxide or other insulating substrates in order to be generally useful, e.g., for device fabrication. The on‐surface coupling method will be straightforwardly applicable to other molecular nanowires that form by surface‐assisted Ullmann coupling,20 and can also be used for other interesting single‐layer transition metal dichalcogenides (TMDC) system that have been successfully realized on Au(111) 51…”