AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS3-TuM

Paper SS3-TuM4
The Chemical and Catalytic Activity of Au/TiO@sub 2@(110) towards Sulfur Dioxide

Tuesday, November 5, 2002, 9:20 am, Room C-112C

Session: Metals, Adsorbates, and Defects on TiO@sub 2@
Presenter: Z. Chang, Brookhaven National Laboratory
Authors: Z. Chang, Brookhaven National Laboratory
J.A. Rodriguez, Brookhaven National Laboratory
G. Liu, Brookhaven National Laboratory
T. Jirsak, Brookhaven National Laboratory
J. Hrbek, Brookhaven National Laboratory
J. Dvorak, Brookhaven National Laboratory
A. Maiti, Accelrys Inc.
Correspondent: Click to Email
Bulk metallic gold typically exhibits a very low chemical and catalytic activity. Recently gold has become the subject of a lot of attention due to its unusual catalytic properties when dispersed on some oxide supports. Gold particles supported on titania are active catalyst for the low temperature oxidation of CO, the selective oxidation of propene, and photocatalytic oxidations used for environmental cleanup. We used synchrotron-based high-resolution photoemission and first-principles density-functional slab calculations to study the interaction of gold with titania and the chemistry of SO@sub 2@ on Au/TiO@sub 2@(110) surfaces. Au/TiO@sub 2@ is much more chemically active than metallic gold or stoichiometric titania. On Au(111) and rough polycrystalline surfaces of gold, SO@sub 2@ bonds weakly and desorbs intact at temperatures below 200 K. For the adsorption of SO@sub 2@ on TiO@sub 2@(110) at 300 K, SO@sub 4@ is the only product. In contract, Au/TiO@sub 2@(110) surfaces fully dissociate the SO@sub 2@ molecule under identical reaction conditions. Interactions with titania electronically perturb gold, making it more chemically active. Furthermore, our experimental and theoretical results show quite clearly that not only gold is perturbed when gold and titania interact. The adsorbed gold, on its part, enhances the reactivity of titania by facilitating the migration of O vacancies from the bulk to the surface of the oxide. In general, the complex coupling of these phenomena must be taken into consideration when trying to explain the unusual chemical and catalytic activity of Au/TiO@sub 2@. The research was carried out at BNL under Contract No. DE-AC02-98CH10086 with the U.S. DOE (Division of Chemical Sciences).