| AVS 61st International Symposium & Exhibition | |
| Surface Science | Monday Sessions |
| Session SS+EN-MoM |
| Session: | Photocatalysis and Photochemistry at Surfaces |
| Presenter: | Nikolay Petrik, Pacific Northwest National Laboratory |
| Authors: | N.G. Petrik, Pacific Northwest National Laboratory M.A. Henderson, Pacific Northwest National Laboratory G.A. Kimmel, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
TiO2 is an important photocatalyst with many practical applications. However, fundamental understanding of thermal and non-thermal reactions on TiO2 surfaces is still lacking. We have investigated the ultraviolet (UV) photon-stimulated reactions acetone and oxygen adsorbed on reduced rutile TiO2(110). Previous research suggests that a thermal reaction between acetone and chemisorbed oxygen forms acetone diolate – a photochemically active product.1 During UV irradiation, a methyl radical is ejected leaving acetate on the surface. Using infrared reflection absorption spectroscopy, we have identified the acetone diolate, which degrades during UV irradiation forming a new product. We have also measured the angular distribution of the photodesorbing methyl radicals, which is consistent with their ejection from the acetone diolate. Specifically, a peak in the distribution near ~60° to the surface normal is detected in the plane perpendicular to the BBO rows. However, we have also observed a second channel for photo-ejection of methyl radical for larger acetone:O2 ratios. It manifests itself with a photodesorption peak normal to the surface and slower signal decay kinetics. These studies provide new insights into mechanisms responsible for the photochemistry of small molecules on TiO2 and other oxide surfaces. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. The work was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL) . PNNL is a multiprogram national laboratory operated for DOE by Battelle under Contract DE-AC05-76RL01830 .
(1) Henderson, M. A. Relationship of O2 Photodesorption in Photooxidation of Acetone on TiO2 . J. Phys. Chem. C, 2008 ,112, 11433-11440.