Insight the process of hydrazine gas adsorption on layered WS ₂ : a first principle study

Abstract

The process of hydrazine gas adsorption on layered WS₂ has been systematically studied from first principle calculations. Our results demonstrate that this adsorption process is exothermic, and hydrazine molecules are physically adsorbed. The layer-dependent adsorption energy and interlayer separation induced by van der Waals interaction exerted by hydrazine molecules lead to the difficulty in desorbing hydrazine molecules from layered WS₂ as the number of layers increases. The most interesting finding is the emergence of localized impurity states below the Fermi level upon the hydrazine adsorption, irrespective of the number of WS₂ layers, resulting in a significant effect on the band structures and subsequently changing its electrical conductivity. Furthermore, a layer-dependent small charge transfer occurs between hydrazine and layered WS₂, leading to a charge redistribution and considerable polarization in the adsorbed systems. The existence of defects and the humidity, on the other hand, influences the sensitivity of layered WS₂ to the hydrazine adsorption. Obtained results show that a perfectly layered WS₂ might be a promising candidate as an efficient nanosensor to detect such toxic gas in dry environment.