DFT studies of elemental mercury oxidation mechanism by gaseous advanced oxidation method: Co-interaction with H2O2 on Fe3O4 (111) surface

摘要

Density functional theory calculations have been carried out for H2O2 and Hg-0 co-interaction on Fe3O4 (111) surface. On the Fe-tet1-terminated Fe3O4 (111) surface, the most favored configurations are H(2)O(2 )decomposition and produce two OH groups, which have strong interaction with Hg atom to form an OH-Hg-OH intermediate. The adsorbed OH-Hg-OH is stable and hardly detaches from the catalyst surface due to the highly endothermic process. A large amount of electron transfer has been found from Hg to the produced OH groups and has little irreversible effect on the Fe3O4 (111) surface. On the Fe-oct2- terminated Fe3O4 (111) surface, the Fe-oct2 site is more active than Fe-tet1 site. H2O2 decomposition and Hg-0 oxidation processes are more likely to occur due to that the Fe-oct2 site both contains Fe2+ and Fe3+ cations. The calculations reveal that Hg-0 oxidation by the OH radical produced from H2O2 is energetically favored. Additionally, Hg-0 and H2O2 co-interaction mechanism on the Fe3O4 (111) interface has been investigated on the basis of partial local density of state calculation. (C) 2017 Elsevier B.V. All rights reserved.