DFT insights to mercury species mechanism on pure and Mn doped Fe3O4(1 1 1) surfaces

Abstract

The interaction between mercury species and Fe3O4(1 1 1), Mn doped Fe3O4(1 1 1) surfaces, with Feoct2- termination has been calculated by density functional theory (DFT). Different adsorption sites and placement of adsorbates, potential catalytic oxidation of Hg0 by the adsorbed Cl atoms on the Mn-doped Fe3O4 surface have been considered. The result revealed Hg0 physical and weak chemical adsorption on both pure surface and Mn-doped surface. Horizontally placed HgCl and HgCl2 were better chemisorbed on the surface. Although complete dissociation and partial dissociation occurred during the adsorption process of oxidation mercury, configurations of complete dissociation were more stable than that of partial dissociation. HgCl was chemically adsorbed on both Fe3O4 (1 1 1) and Mn doped Fe3O4 (1 1 1) surface through breaking into two atoms, and HgCl2 adsorbed through three ones. Both of the Cl atom and Hg atom tended to bind to the transition metals on the surface. When Mn and Fe atoms coexisted on the surface, Cl atoms preferred to bind to Mn atoms. Besides, all the decomposition reaction was exothermic process according to the negative values of adsorption energy.