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Lookup NU author(s): Dr Terry Egerton, Ian Tooley
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Photogreying, the change in brightness on UV irradiation in the absence of oxygen, of TiO2 nanoparticulate dispersions is shown to depend on the nature of the liquid, consistent with a surface reaction. Measurements on a series of TiO2 particles (mainly 75×10 nm) dispersed in, e.g., alkyl benzoate correlate well with those on the same TiO2's dispersed in a second liquid (e.g. propan-2-ol). Photogreying in propan-2-ol is paralleled by photocatalytic-oxidation activity, indicating a common origin - UV-generation of charge carriers. Further, photogreying parallels Ti 3+ formation. Hence, although appearance and the visible spectra of photogreyed particles both differ from those of Ti3+ in ≤ 10 nm colloidal TiO2, we suggest that photogreying is caused by capture of UV excited electrons to form Ti3+. Surface treatment reduces photogreying, and we speculate that differences between uncoated samples reflect differences in the number of potentially reducible Ti's. © 2006 Springer Science+Business Media, Inc.
Author(s): Egerton TA, Kessell LM, Tooley IR, Wang L
Publication type: Article
Publication status: Published
Journal: Journal of Nanoparticle Research
Year: 2007
Volume: 9
Issue: 2
Pages: 251-260
ISSN (print): 1388-0764
ISSN (electronic): 1572-896X
Publisher: Springer Netherlands
URL: http://dx.doi.org/10.1007/s11051-006-9195-1
DOI: 10.1007/s11051-006-9195-1
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