Rhenium Disulfide

The group-VI members such as molybdenum and tungsten are the most typical ones, but group-VII rhenium disulfide has been attracting most attention of late because of its unusual structural, electro-optical and chemical properties; especially an indirect-to-direct band-gap transition which occurs when thinned down from bulk to monolayer. The group-VI transition-metal dichalcogenides have a 1H, 2H, 3R or 1T structure, whereas ReS2 has a distorted 1T structure which imparts an in-plane anisotropy to its physical properties. Few other materials (black phosphorus, ReSe2, TiS3, ZrS3) exhibit such an in-plane structural anisotropy. This makes ReS2 unique among the transition-metal chalcogenides. Atomically thin rhenium disulphide is characterized by weak interlayer coupling and a distorted 1T structure, which leads to the anisotropy in optical and electrical properties. It also possesses structural and vibrational anisotropy, layer-independent electrical and optical properties and metal-free magnetism. In these respects, it differs from group-VI transition-metal dichalcogenides such as MoS2, MoSe2, WS2 and WSe2. It is already being used in solid-state electronics, catalysis, energy storage and energy-harvesting applications.