Molecular metal oxide cluster-surface modified titanium (IV) dioxide photocatalysts

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2012-01
Authors
Nolan, Michael
Iwaszuk, Anna
Tada, Hiroaki
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CSIRO Publishing
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Abstract
The surface modification of TiO2 with molecular sized metal oxide clusters has recently been shown to be a promising approach for providing TiO2 with visible-light activity and/or improved UV activity. This short review summarizes the effects of the surface modification of TiO2 with the oxides of iron and tin selected from d- and p-blocks, respectively, on the photocatalytic activity. Fe(acac)(3) and [Sn(acac)(2)]Cl-2 chemisorption on the TiO2 surface occurs by ligand-exchange and ion-exchange, respectively. Taking advantage of the strong adsorption, we formed extremely small metal oxide clusters on TiO2 by the chemisorption-calcination cycle (CCC) technique with their loading amount strictly controlled. The iron oxide surface modification of P-25 (anatase/rutile = 4: 1, w/w, Degussa) gives rise to a high level of visible-light activity and a concomitant increase in the UV-light activity for the degradation of model organic pollutants. On the other hand, only the UV-light activity is increased by the tin oxide surface modification of ST-01 (anatase, Ishihara Sangyo). This striking difference can be rationalized on the basis of the material characterization and DFT calculations, which show that FeOx surface modification of rutile leads to visible-light activity, while SnO2-modified anatase enhances only the UV-light activity. We propose the mechanisms behind the FeOx and SnO2 surface modification, where the surface-to-bulk and bulk-to-surface interfacial electron transfer are taken into account in the former and the latter, respectively.
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Bilayer-type photocatalyst , Visible-light photocatalysis , TiO2 photocatalysis , Band-gap , Semiconductor , Irradiation , Transition , Particles , Anatase , Design , Adsorption , Chemisorption , Degradation , Density functional theory , Ion exchange , Iron oxides , Loading , Metallic compounds , Organic conductors , Oxide minerals , Photocatalysis , Photocatalysts , Surfaces , Tin , Tin oxides , Titanium
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Nolan, M., Iwaszuk, A. and Tada, H. (2012) 'Molecular metal oxide cluster-surface modified titanium (IV) dioxide photocatalysts', Australian Journal of Chemistry, 65(6), pp. 624-632. doi: 10.1071/CH11451
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© CSIRO 2012.