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Photoactive TiO₂ Nanopowder Synthesized at Low Temperature without a Catalyst

J.-P. Nikkanen¹, E. Huttunen-Saarivirta¹, T. Kanerva¹, T. Kivelä², E. Levänen³, T. Mäntylä³

¹ Tampere University of Technology, Department of Materials Science, P. O. Box 589, FIN-33101 Tampere, Finland
² University of Helsinki, Department of Chemistry, P.O. Box 55, FI00014 Helsinki, Finland
³ Tampere University of Technology, Department of Materials Science, P. O. Box 589, FIN-33101 Tampere, Finland

received February 14, 2011, received in revised form March 6, 2011, accepted March 14, 2011

Vol.2, No.2, Pages 97-102   DOI: 10.4416/JCST2011-00008

Abstract

Nanocrystalline titanium dioxide (TiO₂) anatase powder was synthesized at 50 °C under normal pressure using the sol-gel method without a base or acid catalyst. The structural and photocatalytic properties of the produced anatase powder were determined with X-ray diffraction, transmission electron microscopy and nitrogen adsorption testing, and compared to those of anatase powder synthesized in a conventional process by calcining at 450 °C. The photocatalytic activity was confirmed with methylene blue (MB) discoloration tests.

The obtained results showed that the crystal size of anatase produced with the low-temperature catalyst-free method averaged 5.5 nm, while it was 12 nm for the anatase made by calcining. As a consequence, the specific surface area of the anatase powder synthesized at low temperature was three times higher than that of the calcined powder. The weight-based photocatalytic activity of the low-temperature-synthesized powder was 2.5 times higher than that of calcined powder. Therefore, the activity per unit of surface area was slightly higher for calcined anatase.

Keywords

Sol-gel processes, titanium dioxide, anatase, grain growth, calcination

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Göller Verlag GmbH

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