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Journal of Nanomaterials
Volume 2010, Article ID 512785, 10 pages
Research Article

Effect of Postdeposition Heat Treatment on the Crystallinity, Size, and Photocatalytic Activity of Nanoparticles Produced via Chemical Vapour Deposition

Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Putra, 43400 Serdang, Selangor, Malaysia

Received 7 December 2009; Revised 27 March 2010; Accepted 8 May 2010

Academic Editor: Theodore Tsotsis

Copyright © 2010 Siti Hajar Othman 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.


Titanium dioxide () nanoparticles were produced using chemical vapour deposition (CVD) at different deposition temperatures (300–700°C). All the samples were heat treated at their respective deposition temperatures and at a fixed temperature of 400°C. A scanning electron microscope (SEM), a transmission electron microscope (TEM), and X-ray diffraction (XRD) were used to characterize the nanoparticles in terms of size and crystallinity. The photocatalytic activity was investigated via degradation of methylene blue under UV light. The effects of post deposition heat treatment are discussed in terms of crystallinity, nanoparticle size as well as photocatalytic activity. Crystallinity was found to have a much larger impact on photocatalytic activity compared to nanoparticle size. Samples having a higher degree of crystallinity were more photocatalytically active despite being relatively larger in size. Surprisingly, the photocatalytic activity of the samples reduced when heat treated at temperatures lower than the deposition temperature despite showing an improvement in crystallinity.