AVS 52nd International Symposium
    Surface Science Monday Sessions
       Session SS2-MoA

Paper SS2-MoA4
The Multiple Roles of Oxygen in Organic Photo-oxidation on TiO2: Insights from Studies on a Model Photocatalyst Surface

Monday, October 31, 2005, 3:00 pm, Room 203

Session: Oxide Surfaces Structure and Reactivity
Presenter: M.A. Henderson, Pacific Northwest National Laboratory
Authors: M.A. Henderson, Pacific Northwest National Laboratory
J.M. White, University of Texas at Austin
M.D. Robbins, University of Texas at Austin
H. Uetsuka, Kanagawa Academy of Science and Technology, Japan
H. Onishi, Kobe University, Japan
Correspondent: Click to Email
The primary role that molecular oxygen has been viewed to play in organic photo-oxidation processes on high surface area TiO@sub 2@ photocatalysts has traditionally been restricted to that of an electron scavenger. However, some groups have proposed more direct involvement of O@sub 2@ in reactions with organics. Typical photocatalytic studies employ high surface area powders which are often difficult to characterize on the molecular scale. Results presented in this talk on a model TiO@sub 2@ photocatalyst, rutile TiO@sub 2@(110), provide more detailed information on the roles of O@sub 2@ and show that O@sub 2@ not only acts as an electron scavenger but also: is involved in thermal reactions with organics and OH groups, blocks organic adsorption sites, and competes with adsorbed organics for photo-generated holes. Results on the photo-oxidation of trimethyl acetate, isobutene and acetone will be used to illustrate these functions of O@sub 2@ during photocatalysis on TiO@sub 2@. Additionally, it will be shown that the function of oxygen oscillates through these different roles as a typical C@sub n@ hydrocarbon is oxidized to completion (i.e., to CO@sub 2@ and water) by sequential removal of C@sub 1@ units.