A comprehensive DFT study of the stabilization of methyl-mercury over Ag nanoparticles

Abstract

The surface structure of Nanoparticles (NPs) gives distinct interfacial chemical characteristics to individual facets, and it can control the capacity of MeHg adsorption at these interfaces. Here we propose a theoretical model based on the actual properties of the Ag NPs and perform a comparative study on the MeHg adsorption properties of different surfaces ((1 1 1), (1 1 0), (1 0 0), and (2 1 1)) based on the first-principles theoretical study. It is found that each surface of the NPs has a strong affinity (greater than 2 eV) for MeHg despite differences in surface structure. To better understand the electron interaction of adsorbed MeHg with each surface of Ag NPs, the electronic charge density difference, the partial density of states (PDOS), and the Bader charge were investigated. Furthermore, the energy barrier of MeHg diffusion on the facets of Ag NPs was calculated. The difficulty of MeHg diffusion on various facets of Ag NPs is follow the trend of (1 0 0) > (1 1 0) > (2 1 1) > (1 1 1). In virtue of its superior diffusivity and high affinity for MeHg, the prospect of Ag NPs application in MeHg removal in liquids is highly promising. This work could provide a new strategy to applied metal NPs as a scavenger material for MeHg in liquid conditions.