Photocatalytic activity of metal ion (Fe or W) doped titania
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Photocatalytic Activity of Metal Ion (Fe or W) Doped Titania Sang Soo Lee, Hyun ,long Kim, Kyung Tack Jung, Hak Soo Kim* and Yong Gun Shuf Department of Chemical Engineering. Yonsei University, Seoul 120-749, Korea *Department of Chemical Engineering, Sunmoon University, Chung-nam 336-708, Korea (Receh,ed 7 September 200t 9 accepted 13 October 2001)
Abstraet-lron or tungsten-doped nano TiO, were successfully synthesized from TiCi,. All of the samples showed anatase phase of TiO_,. For the iron-doped riO_,, Iron ion was well dispersed in the TiO_, lattice. Hm~.ever, tungstendoped TiQ, formed 12-tungstate \~.ith anatase "l'i()e. As the concentration of tungsten increased, 12-tungstate disappeared. The photoeatalytic oxidation of acetaldehyde was evaluated to exmnine the photocatalytic characteristics of metal-doped Tit)_,. Because of the surface containing metal oxide or metal precursors at high concentration metal ion, increasing the concentration of W or Fe ion decreased the reactivity', The reaction rate was drastically increased aIicr 3t10 ~ heat treatment. Furthermore, the phou)eatalytic activity of iron- or tungsten-doped TiO, was higher than that of synthesized pure TiO: and commercial TiOz. Key words: Photocatalysis. Photoeatalyst, TR),. Metal-Doped TiO_,
INTRODUCTON
ergy level of the dopants within the T i ~ lattice, their d-electronic configuration, the distribution of dopants, the electron-donor concentralion, and the li~t intensity [tloffmann et al., 19951. Some brief mentions to this subject have appeared in the literature, but there does not exist a complete and exhaustive revision [Litter et al., 1996]. In this paper, titania particles were prepared from TiCI4, The use of inorganic salt precursor rather than organic alkoxide precursor not only can reduce the cost of synthesis, but also can avoid the use of organic solvent to decrease pollution. And, we doped the iron or tungsten ion on the Ti(~ particles to improve the photocatalytic characteristics. Photodegradation of acetaldehyde was tested to examine a number of preparation variables which affect the photocatalytic activity of Fe- or W-doped "l'i~ catalyst.
Photocata[ytic oxidation of volatile organic compounds in water and air has received much attention as a potential technology of pollution abatement. Heterogeneous photocatalysis is the ambient temperature process in which the surface of an illuminated semiconductor acts as a chemical reaction catalyst by using band gap light. These semiconductor compounds usually have a moderate energy band gap ( 1-3.7 eV) between their valence and conduction bands. The semiconductor photocatalyst for the reaction nmst be ( f ) pholoactive: (2) able to utilize visible and/or near-UV light: (3) biologically and chemically inert; (4) photostable, i.e., not liable to photoanodic corrosion for example: (5) inexpensive [Mills et al., 19971. By common consent, the T i ~ satisfies criteria (1)-(5) and is one of the best semiconductors for photocatalytic reactions. Many researchers have proved that T i ~ is an exce
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