Theoretical Investigation of CO Adsorption on Clean and Hydroxylated TiO2-B (100) Surfaces

Abstract

CO adsorption on both clean and hydroxylated TiO2-B (100) surfaces with terminal and bridging hydroxyl groups is investigated via first-principles density functional theory calculations. The adsorption mechanisms of CO molecules on both clean and hydroxylated surfaces are discussed. CO molecules preferentially adsorb at five coordinated Ti sites of TiO2 through C atoms. The calculated adsorption energies range from 13.11 to 43.03 kJ/mol. Moreover, lower concentrations of CO gas can strongly bind to the surface. From structure point of view, CO molecules interact with the surface mainly via its 2π* state. The adsorption is accompanied by electron transfers (0.02−0.08 e) between the CO molecule and the surface. Both the terminal and bridging hydroxyl groups can slightly facilitate CO adsorption, however, in different levels. When CO molecules adsorb near the bridging hydroxyl groups (Eads = 43.56 kJ/mol), it can increase more CO adsorption than the terminal hydroxyl groups (Eads = 33.87 kJ/mol). Furthermore...