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Photodesorption of Organic Radicals from TiO2(110)


EMSL Project ID
26715

Abstract

We propose examining the role that photodesorption processes play in heterogeneous photocatalytic decomposition of organics over titanium dioxide using the rutile TiO2(110) and anatase TiO2(001) surfaces as prototypical photocatalysts. Recent work for acetone has shown that methyl radicals are ejected from the TiO2(110) surface during the single step photodecomposition of acetone to acetate.1 In fact, results in that study strongly suggest that, at least in the case of acetone, methyl radical photodesorption constitutes the main mechanistic pathway by which this common organic molecule is photodecomposed over this surface. We propose examining this assertion in detail by conducting studies in which (1) the effect of TiO2 polymorph is explored (i.e., anatase versus rutile), (2) the coverage and reaction conditions are varied, and (3) ligand substituent effects are explored. In the latter, we will examine how substitution of one of the methyl groups on the acetone molecule with a different ligand (e.g., a phenyl group) affects the yield and temporal evolution of methyl radical during UV irradiation. These results will demonstrate to a great extent the mechanistic significance of organic radical desorption in organic photooxidation reactions on TiO2 surfaces.

Project Details

Project type
Exploratory Research
Start Date
2007-08-01
End Date
2008-08-03
Status
Closed

Team

Principal Investigator

Michael Henderson
Institution
Pacific Northwest National Laboratory

Related Publications

Zehr RT, and MA Henderson. 2008. "Influence of O2-induced surface roughening on the chemistry of water on TiO2(110)." Applied Surface Science 602(8):1507-1516.