Density Functional Theory Study Adsorption Of Small Molecules On Perovskites Compound Oxide

In this paper, the surface properties and adsorptions of NO on surface of SrTiO3 and BaTiO3 with perovskite-type structure were investigated by the quantum chemistry calculation. The difference between surface and bulk was explained; furthermore, the catalysis activities for NO were estimated. The surface of O-defect SrTiO3-x(001) and the interaction of NO with this surface are calculated.Not only the surface structurse(displacement of z coordination, relaxation) and electric structures(band structure, density of states, electronic density redistribution) of SrTiO3(001) and BaTiO3(001), but also these properties of SrTiO3-x(001) with oxygen vacancies are studied by the quantum chemistry soft which based on the density functional theory (DFT) and pseudopotential. The electronic structures of adsorptions of NO on SrTiO3(001), SrTiO3-x(001) and BaTiO3(001) were investigated. The calculated results agree with the experimental values and previous theoretical values. For the surface of SrTiO3(001), the results of surface structure showed that the surface relaxation by the atoms perpendicular to surface occurred for both possible terminations(SrO and TiO2 terminations), which lead to the surface polarization; for the surface of BaTiO3(001), the surface relaxation of SrO terminated surface is the same to the SrTiO3(001) surface. For the TiO2 terminated surface of BaTiO3(001), except for the displacement in the direction perpendicular to the surface, lateral displacement(x and y planes) exists in the uppermost layers. From the results of electronic structures, we demonstrated the charge in the surface redistributed. We calculated the band structure and density of states(DOSs), the results showed the band gap of SrO terminated surface is the same to bulk; and the gap of TiO2 terminated surface has a substantial reduction than bulk. The results of adsorption energy, bond length and Mulliken populations analysis demonstrated the catalysis activity for NO of SrTiO3-x(001) with oxygen vacancies is higher than perfect SrTiO3(001)surface. The perfect surfaces of SrTiO3(001) and BaTiO3(001) have a little activities for the decomposition of NO. In the perfect surface, the activity of TiO2 terminated surface is higher than...