DFT study of mercury adsorption on ot-Fe_2O_3 surface: Role of oxygen

摘要

First-principle calculations based on density functional theory were performed to investigate the micro-mechanism of Hg~0 adsorption on α-Fe_2O_3 (001) surface in the presence of O_2. Considering O_2 is more easily adsorbed on α-Fe_2O_3 than Hg~0, this paper investigated Hg~0 adsorption on O_2 embedded α-Fe_2O_3 (001) surface to clarify the effect of O_2 on the capture of mercury by α-Fe_2O_3. 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/α-Fe_2O_3 (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.