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DS: Fachverband Dünne Schichten

DS 43: Biomolecular and Functional Organic Layers II (Focused Session)

DS 43.3: Vortrag

Freitag, 26. März 2010, 12:00–12:15, H2

Monitoring photooxidation of acetone on TiO₂(110) using IR spectroscopy — •Youkun Gao¹, Mingchun Xu¹, Yuemin Wang¹, and Christof Wöll² — ¹Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum, 44801 Bochum, Germany — ²Institut für Funktionelle Grenzflächen (IFG), Karlsruher Institut für Technologie, 76021 Karlsruhe, Germany

The photochemistry on semiconductor TiO₂ surfaces has recently received enormous attention from both fundamental and technological perspectives because of its extensive applications related to energy conversion and other associated processes with environmental impact. There is much interest in the heterogeneous photooxidation of acetone on TiO₂. Whereas acetone photooxidation has been extensively studied on TiO₂ powder samples there is, due to experimental difficulties, a general lack of information on single-crystal surfaces. In this work, we report the first IR studies of acetone photoreactions on the TiO₂(110) surface using reflection-absorption infrared spectroscopy (RAIRS). Exposing TiO₂ to acetone at 110 K leads to molecular (associatve) adsorption, forming mono- and multilayers. The dark reaction of acetone with oxygen molecules on this TiO₂ surface leads to the formation of η²- diolate species. Irradiation with UV light leads to a conversion of this species to acetate via methyl radical ejection. Furthermore, we found that carbonate/bicarbonate is the final oxidation product after extended exposure to UV light. Finally, the quantum yield and photo-reaction cross section Q for photo-induced oxidation of acetone on differently modified TiO₂(110) surfaces were determined.