title: The critical role of water at the gold-titania interface in catalytic CO oxidation.
abstract: We provide direct evidence of a water-mediated reaction mechanism for room-temperature CO oxidation over Au/TiO2 catalysts. A hydrogen/deuterium kinetic isotope effect of nearly 2 implicates O-H(D) bond breaking in the rate-determining step. Kinetics and in situ infrared spectroscopy experiments showed that the coverage of weakly adsorbed water on TiO2 largely determines catalyst activity by changing the number of active sites. Density functional theory calculations indicated that proton transfer at the metal-support interface facilitates O2 binding and activation; the resulting Au-OOH species readily reacts with adsorbed Au-CO, yielding Au-COOH. Au-COOH decomposition involves proton transfer to water and was suggested to be rate determining. These results provide a unified explanation to disparate literature results, clearly defining the mechanistic roles of water, support OH groups, and the metal-support interface.
authors.affiliation: Department of Chemistry, Trinity University, San Antonio, TX 78212-7200, USA.
authors.forename: Johnny
authors.initials: J
authors.lastname: Saavedra
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204-4004, USA.
authors.forename: Hieu A
authors.initials: HA
authors.lastname: Doan
authors.affiliation: Department of Chemistry, Trinity University, San Antonio, TX 78212-7200, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Pursell
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204-4004, USA. bert.chandler@trinity.edu grabow@uh.edu.
authors.forename: Lars C
authors.initials: LC
authors.lastname: Grabow
authors.affiliation: Department of Chemistry, Trinity University, San Antonio, TX 78212-7200, USA. bert.chandler@trinity.edu grabow@uh.edu.
authors.forename: Bert D
authors.initials: BD
authors.lastname: Chandler