Density functional theory study of the adsorption of elemental mercury on a 1T-MoS₂ monolayer

Elemental mercury has become a global concern because of its significant impact on human health and the ecosystem. A lot of effort has been put towards the removal of elemental mercury from the 2H-MoS₂ (prismatic structure of MoS₂). However, the mechanism of 1T-MoS₂ (polytype structure of MoS₂) in Hg⁰ capture remains unexplored. In this study, density functional theory (DFT) was adopted to investigate the adsorption mechanism of Hg on a 1T-MoS₂ monolayer. The different possible adsorption positions on the 1T-MoS₂ were examined. For different adsorption configurations, the changes in electronic property were also studied to understand the adsorption process. The results elucidated that chemisorption dominates the adsorption between Hg⁰ atoms and the 1T-MoS₂. It was found that the T_Mo (on top of the Mo atom) position is the strongest adsorption configuration among all the possible adsorption positions. The adsorption of Hg⁰ atoms on the 1T-MoS₂ monolayer is influenced by adjacent S and Mo atoms. The adsorbate Hg0 atom is found being oxidized on the T_Mo position of the 1T-MoS₂ with an adsorption energy of −1.091 eV. From the partial density of states (PDOS) analysis of the atoms, the strong interaction between Hg⁰ and the 1T-MoS₂ surface is caused by the significant overlap among the d orbitals of the mercury atom and the s orbital of the S atom and p and d orbitals of the Mo atom.