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TitleTransparent, photocatalytic, titania thin films formed at low temperature
Publication TypeJournal Article
Year of Publication2013
AuthorsKemmitt, T., Al-Salim N.I., Lian J., Golovko V.B., and Ruzicka J.-Y.
JournalCurrent Applied Physics
Pagination142 - 147
Date Published2013
ISSN15671739 (ISSN)
KeywordsAromatic compounds, Cast film, Curing, Decoloration, Ethanol, Hydrothermal processing, Infrared spectroscopy, Inorganic residues, Iso-propoxide, Low level, Low temperatures, Methylene blue, Mineral acid, Mineral phase, Molar ratio, Organic acids, Organic components, oxalic acid, Oxide minerals, Peptization, Photo-catalytic, Photo-decomposition, Photoactivity, Photocatalysis, Photocatalytic activities, Sol-gels, Thin films, TiO, Titania, Titania thin films, Titanium, titanium dioxide, Ultraviolet visible spectroscopy, UV-vis spectroscopy, Visible light region
AbstractA convenient method for the preparation of transparent, photocatalytic titania thin films is described. The films do not require annealing or thermal processing to develop photoactivity, thus can be applied to many thermally-sensitive substrates. Oxalic acid is used in place of the usual mineral acids to peptize the precipitated hydrous titania formed from the hydrolysis of titanium iso-propoxide. This leaves no inorganic residues in the film resulting in a higher quality film. The mineral phase and the photocatalytic activity produced are strongly influenced by the ratio of oxalic acid:titanium iso-propoxide employed. The peptization is carried out at 65 °C with vigorous stirring for 1 h in water containing 15% v/v ethanol, followed by a hydrothermal step at 95 °C. High oxalic acid:Ti molar ratios (0.5:1) result in rutile free sols, while lower ratios (0.25:1) result in anatase, rutile, brookite and TiO 2(B) in varying proportions. The films were exposed to low level UV light to cure, and photodecompose the residual organic components in the film. The photodecomposition of residual oxalic acid in the cast films were monitored using infrared spectroscopy. Photo-activity of the UV-cured films was compared by monitoring the decoloration of methylene blue stains on the film, by UV-Vis spectroscopy. Transmission was greater than 99% across the visible light region (400-800 nm). © 2012 Elsevier B.V. All rights reserved.

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