Lithium Exfoliated Vanadium Dichalcogenides (VS2, VSe2, VTe2) Exhibit Dramatically Different Properties from Their Bulk Counterparts

Ultrathin 2D transition metal dichalcogenides (TMDs) have attracted widespread attention due to their excellent electrical, optical, and electrochemical properties. Ultrathin vanadium disulfide is a metallic member of two dimensional materials aside graphene which does not possess a bandgap in the electronic structure. Research on vanadium disulfide reveals its versatile application, such as supercapacitor, battery material, electrocatalyst, and moisture sensor. Considering the superior performance of vanadium disulfide, it is necessary and essential to study vanadium diselenide and vanadium ditelluride. In this study, an effort has been devoted to study the inherent electrochemistry of three vanadium dichalcogenides (VX2: VS2, VSe2, and VTe2) and explore their potential as electrocatalysts for hydrogen evolution reaction. Following the exfoliation routes established for MoS2 and WS2, Li intercalation route, using n-buthyllithium is utilized. Interestingly, upon exfoliation to single/few layer VX2 become partly converted to nonstoichiometric vanadium oxide and lithium vanadates, which is strikingly different when compared to group 6 TMDs, such as MoX2 and WX2.