Theoretical study of Au20/WS2 composite material as a potential candidate for the capture of XO (X=C, N, S) gases

Abstract

Abstract In this study, density functional theory (DFT) calculations were carried out to understand the structural stability of the interaction of Au20 pyramidal cluster on the tungsten disulfide (WS2) monolayer. According to the adsorption energy values, the predominant interaction in this system (Au20/WS2) corresponds to chemisorption (−4.68\xa0eV). This behavior is also reproduced by small gold clusters (Aun, n\xa0=\xa03, 5, 9, 13 and 16). The Au20/WS2 composite system presents a mechanism of interaction influenced by the charge transfer from the Au20 cluster to the WS2 monolayer. The structural stability was corroborated by ab-initio molecular dynamics (AIMD) calculations, which exhibits how the WS2 monolayer is a good support for transition metals such as Au clusters. According to the analysis of the electronic and optical properties, the Au20/WS2 composite system has a semi-metallic behavior, based on to the band spectrum (0.65\xa0eV). The optical properties of the Au20/WS2 composite system exhibits a broad absorption spectrum of visible light, in contrast to the isolated Au20 cluster and the WS2 monolayer. The performance of this composite material in the adsorption process of the XO (X\xa0=\xa0C, N, and S) molecule was also evaluated. The interaction between the XO molecule and the Au atoms shows a favorable formation of bonding with a van der Waals (vdW) type interaction, according to the critical points analysis. Our results show high adsorption energy values in all active sites of the Au20 cluster. This kind of composite system provide a structural idea, about the use of the WS2 monolayer as a support of transition metals at the nanoscale level for the capture of polluting gases.