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Journal of Nanomaterials
Volume 2006 (2006), Article ID 78902, 8 pages
http://dx.doi.org/10.1155/JNM/2006/78902

Photocatalytic Oxidation of a Volatile Organic Component of Acetaldehyde Using Titanium Oxide Nanotubes

1Department of Geology and Geophysics and Material Science Program, University of Wisconsin, 1215 West Dayton Street, Madison, WI 53706, USA
2Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131, USA
3Los Alamos National Laboratory, Engineering Science and Applications Division, MS C390, Los Alamos, NM 87545, USA
4Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185, USA

Received 14 February 2006; Revised 9 November 2006; Accepted 22 December 2006

Copyright © 2006 Huifang Xu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Titanium oxide nanotubes are prepared and treated with Au (Au/nanotube sample) and Pt (Pt/nanotube sample), and the photoactivity of these catalysts compared to a standard Degussa P25 photocatalyst is investigated. The samples were analyzed using X-ray diffraction, field emission gun scanning transmission electron microscopy (STEM). Both high-resolution TEM images and high-angle annular dark-field (HAAD) images were recorded for the specimens. Oxidation of acetaldehyde was used to test the efficiency of the catalysts. Nanotube samples showed better photoactivity than the standard P25, because the P25 titania deactivates quickly. Enhanced reactivity of the nanotube is related to surface charge polarity developed on outer and inner surfaces due to the difference in overlap of oxygen anions that resulted from curving of octahedral sheets. A tentative and qualitative surface polarity model is proposed for enhancing electron-hole pair separation. The inner surface benefits reduction; whereas, the outer surface benefits oxidation reactions. Both the metal identity and the size of the metal particles in the nanotubes affected the photocatalytic activity. Specifically, the addition of platinum increased the activity significantly, and increased the total yield. The addition of gold had lesser impact compared to the platinum. Formation of Pt large nanoparticles on the nanotube surfaces reduces the oxidation reactivity.