title: Direct Imaging of Site-Specific Photocatalytical Reactions of O2on TiO2(110).
abstract: Photostimulated reactions of single O2molecules on reduced TiO2(110) surfaces were directly observed at an atomic level with high-resolution scanning tunneling microscopy at 50 K. Two distinct reactions of O2desorption and dissociation occur at different active sites of terminal Ti atoms and bridging O vacancies, respectively. Two reaction channels follow very different kinetics. While hole-mediated O2desorption is promptly and fully completed, electron-mediated O2dissociation is much slower and is quenched above some critical O2coverage. Evidently, the O2photochemistry on TiO2(110) is quite more complex than thought previously. Density functional theory calculations indicate that both coordination and charge state of an O2molecule chemisorbed at the specific site largely determine a particular reaction pathway.
authors.affiliation: Environmental Molecular Sciences Laboratory and Institute for Integrated Catalysis, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
authors.forename: Zhi-Tao
authors.initials: ZT
authors.lastname: Wang
authors.affiliation: Department of Chemical Engineering, Worcester Polytechnic Institute , Worcester, Massachusetts 01609, United States.
authors.forename: N A
authors.initials: NA
authors.lastname: Deskins
authors.affiliation: Environmental Molecular Sciences Laboratory and Institute for Integrated Catalysis, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
authors.forename: Igor
authors.initials: I
authors.lastname: Lyubinetsky
keywords: DFT; STM; TiO2; oxygen; photochemistry