Interaction behavior study of HCl on (ZnS)_n (n = 1–12) clusters and HCl effect on Hg⁰ adsorption

Abstract

The interaction behavior of HCl and (ZnS)n (n = 1–12) clusters and HCl effect on Hg0 adsorbed by (ZnS)n have been studied theoretically. The combined genetic algorithm and density functional theory (GA‐DFT) method has been used to obtain the structures of (ZnS)nHCl and (ZnS)nHgHCl (n = 1–12) clusters. The structural properties of (ZnS)nHCl and (ZnS)nHgHCl have been analyzed. The adsorption energies and interaction energies have been calculated. Bond length and bond order analysis has revealed that SH and ZnCl bonds form after HCl adsorbed on (ZnS)n clusters, while Hg0 can only weakly bind with (ZnS)nHCl clusters. According to thermodynamic adsorption analysis, the formation of (ZnS)nHCl clusters from (ZnS)n and HCl are spontaneous because of their negative Gibbs free energy changes. The formation of (ZnS)nHgHCl from (ZnS)nHCl and Hg are nonspontaneous for n = 1–4 and 9, and the Gibbs free energy changes have small negative values for other sizes. Electron localization function and noncovalent interaction (NCI) analysis of (ZnS)10HgHCl manifest that Hg and its nearest Zn form zinc amalgam. Projected density of state study has been performed to obtain the interaction nature of HCl and (ZnS)n clusters and Hg0 adsorption on (ZnS)nHCl clusters. Based on our study, HCl is chemical adsorbed by (ZnS)n clusters except (ZnS)4 cluster. After (ZnS)n adsorbs HCl, Hg0 can physically adsorb on (ZnS)nHCl clusters. The strength of Hg0 on (ZnS)nHCl is comparable to that of Hg0 on (ZnS)n, indicating that HCl can hardly affect the adsorption of Hg0 on ZnS clusters.