Single H/𝑯𝟐 Adsorption on Transition Metal Disulphides (TM𝑺𝟐)

Abstract

2D transition metal disulphides have gained a lot of research interest due to their fantastic electrical, optical, magnetic, and mechanical properties which makes them recommended for electrical and optical applications. More interestingly, they have been proposed as suitable alternatives to Pt hydrogen evolution reaction catalysts as they also exhibit layered structures in which the layers interact through Van der Waals forces. Semiconducting transition metal disulphides in bulk are indirect band gap materials whereas their monolayers exhibit direct band gap. Metallic (1T) phase of transition metal disulphides has been widely studied due to their higher hydrogen evolution reaction activity and the tremendous optical and electrical applications it offers. The successful fabrication of bilayer heterostructures of 1T transition metal disulphides will open opportunities for industry scale HER catalysts and electrical devices applications. In this work, we have analyzed structural, electronic, and energetic properties of monolayer 1T-Mo𝑆2 , 1T-Re𝑆2 , 1T-W𝑆2 and 1T-Pd𝑆2 using density functional theory calculations. Bilayer heterostructures including 1T-Mo𝑆2-Pd𝑆2, 1T-W𝑆2-Pd𝑆2, 1T-Pd𝑆2-Re𝑆2, 1T-Mo𝑆2-W𝑆2 and 1T-W𝑆2 Re𝑆2 have been formed and again density functional calculations have been performed on these heterostructures. It was found that 1T-Mo𝑆2 - Pd𝑆2 , 1T-W𝑆2 - Pd𝑆2 and 1T-Pd𝑆2 - Re𝑆2 can be formed spontaneously and also the bilayer heterostructures composed of two metallic monolayers predict a novel metallic van der Waal solids that might be used in future 2D nanomaterials. Finally, 1T-Mo𝑆2-Pd𝑆2, 1T W𝑆2-Pd𝑆2 were found to be the most stable with adsorption free energy close to zero and can serve as suitable catalysts for hydrogen evolution reaction.