Structure, stability, and electronic and optical properties of TMDC-coinage metal composites: vertical atomically thin self-assembly of Au clusters.

Abstract

Composites of metal clusters supported on transition metal dichalcogenides (TMDCs) often provide promising opportunities for applications in nanoelectronics, catalysis, sensing, etc. In the present investigation, a systematic attempt has been made to unveil the structure and stability of coinage M6 clusters supported on TMDC (MoS2 and WS2) monolayers. The more prominent objective is to explore potential candidates that stabilize the two-dimensional (2D) M6 clusters on their surface. Periodic energy decomposition analysis (pEDA) was carried out to probe the various interaction energy (IE) components that govern the stability of the M6 clusters in the composites. Attention has also been devoted to unravelling the electronic and optical properties of these TMDCs/M6 composites. Moreover, ab initio molecular dynamics (AIMD) simulations were performed to scrutinize the dynamic behaviour of Au cluster on WS2 monolayer. The results reveal that the coinage M6 clusters form energetically more stable composites on MoS2 than WS2 monolayer. It is worth mentioning that WS2 promotes the stability of 2D M6 clusters. Inclusion of dispersion correction marginally altered the geometries of the TMDCs/M6 composites but its impact on the IE values was significant. AIMD simulation explicitly emphasizes that the WS2 surface preferentially facilitates the vertical 2D self-assembling of Au atoms and, interestingly, the planarity is mostly retained during the course of simulations. The adsorption of coinage M6 clusters substantially influences the electronic and optical properties of the TMDCs. HSE06 calculation confirms that the decrease in energy gap is more pronounced in MoS2/M6 composites. The outcomes of this study render fundamental insights into the various TMDCs/M6 composites that would certainly be worthwhile probing for diverse practical applications.