DFT study of mercury adsorption on α-Fe2O3 surface: Role of oxygen

First-principle calculations based on density functional theory were performed to investigate the micro-mechanism of Hg-0 adsorption on alpha-Fe2O3 (001) surface in the presence of O-2. Considering O-2 is more easily adsorbed on alpha-Fe2O3 than Hg-0, this paper investigated Hg-0 adsorption on O-2 embedded alpha-Fe2O3 (001) surface to clarify the effect of O-2 on the capture of mercury by alpha-Fe2O3. Theoretical calculations indicate that O-2 dissociates in two steps on the surface, leaving one O atom to interact with a surface Fe atom. Hg-0 adsorption on O/alpha-Fe2O3 (001) surface belongs to weak chemisorption, and the potential energy diagram is provided. Additionally, the study of coverage shows that O atom coverage has a huge impact on Hg-0 adsorption. The adsorption mechanism of Hg-0 on the surface changes from weak chemisorption into stronger chemisorption as the O coverage increases from 0.25 to 1 mL, with the largest adsorption energy of -268.1 kJ/mol. (C) 2013 Elsevier Ltd. All rights reserved.