Photochromism and Size Effect of WO3 and WO3−TiO2 Aqueous Sol

The chromism of tungsten oxides has been investigated for a long time because of its academic and application importance. In this article the photochromism and its dynamics for a WO3 aqueous sol and WO3−TiO2 mixed sols are studied in detail. The chromic performance of the WO3 aqueous sol is improved...

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Bibliographic Details
Published in:Chemistry of materials 2003-10, Vol.15 (21), p.4039-4045
Main Authors: He, Yuping, Wu, Zhenyu, Fu, Limin, Li, Chaorong, Miao, Yanming, Cao, Li, Fan, Haiming, Zou, Bingsuo
Format: Article
Language:English
Subjects:
Chemistry
Colloidal gels. Colloidal sols
Colloidal state and disperse state
Exact sciences and technology
General and physical chemistry
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Summary:The chromism of tungsten oxides has been investigated for a long time because of its academic and application importance. In this article the photochromism and its dynamics for a WO3 aqueous sol and WO3−TiO2 mixed sols are studied in detail. The chromic performance of the WO3 aqueous sol is improved significantly by adding TiO2 aqueous sol, and shows a clear size effect. The intrinsic absorption peak at around 777 nm from W5+ in WO3 nanocluster, which generally appears at around 1000 nm in a WO3 film, shifts with cluster size because of the quantum confinement effect of delocalized carriers in WO3 nanoclusters. Besides the 777 nm band from W5+ in WO3, a new extrinsic 640 nm band, due to the transient formation of WOCl x species in a WO3 sol in the presence of Cl- and TiO2 nanoclusters, appears after adding TiO2 sol. These results are helpful to the understanding of the chromism of tungsten oxides.
ISSN:0897-4756
1520-5002
DOI:10.1021/cm034116g