Interaction of sulfur with TiO2(1 1 0): photoemission and density-functional studies

Upon adsorption of S2 on TiO2(1 1 0) at 300 K, high-resolution photoemission shows the presence of at least three different types of sulfur species associated with SOx groups and S atoms bonded to the Ti rows or vacancies in the bridging oxygen rows. In addition, Sn species are detected on the oxide surface after dosing sulfur at 100 K. The bonding of sulfur to TiO2(1 1 0) was examined using first-principles density-functional calculations and the periodic supercell approach. The density-functional calculations show important variations in the nature of the bonding depending on the sulfur coverage and the presence of O vacancies on the oxide surface.