Adsorption of SO 2 on Li atoms deposited on MgO (1 0 0) surface: DFT calculations

Abstract

The adsorption of sulfur dioxide molecule (SO 2) on Li atom deposited on the surfaces of metal oxide MgO (1 0 0) on both anionic and defect ( F s-center) sites located on various geometrical defects (terrace, edge and corner) has been studied using density functional theory (DFT) in combination with embedded cluster model. The adsorption energy ( E ads) of SO 2 molecule (S-atom down as well as O-atom down) in different positions on both of O −2 and F s sites is considered. The spin density (SD) distribution due to the presence of Li atom is discussed. The geometrical optimizations have been done for the additive materials and MgO substrate surfaces (terrace, edge and corner). The oxygen vacancy formation energies have been evaluated for MgO substrate surfaces. The ionization potential (IP) for defect free and defect containing of the MgO surfaces has been calculated. The adsorption properties of SO 2 are analyzed in terms of the E ads, the electron donation (basicity), the elongation of S–O bond length and the atomic charges on adsorbed materials. The presence of the Li atom increases the catalytic effect of the anionic O −2 site of MgO substrate surfaces (converted from physisorption to chemisorption). On the other hand, the presence of the Li atom decreases the catalytic effect of the F s-site of MgO substrate surfaces. Generally, the SO 2 molecule is strongly adsorbed (chemisorption) on the MgO substrate surfaces containing F s-center.