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Preparation of Fe3+-doped TiO2 Photocatalyst by Controlled Colloidal Synthesis Method

Author: ChenZhi
Tutor: LiuSong
School: South China University of Technology
Course: Applied Chemistry
Keywords: TiO2 photocatalysis iron ion doping controlled colloidal synthesis
CLC: O643.36
Type: Master's thesis
Year: 2010
Downloads: 118
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Abstract


In order to enhance the photocatalytic activity of TiO2, Iron （III）-doped TiO2 powders photocatalysts were synthesized by sol-gel and controlled colloidal synthesis method （CCS）, and were characterized by XRD, TEM, TG-DSC, BET, UV-vis spectroscopy （DRS） and FS spectra. The samples were employed as catalysts for methyl orange photodegradation in aqueous suspensions under UV irradiation, used as a probe reaction. The influence of iron content, coating times and doping modes on the photocatalytic activities were investigated. The results were showed as follows:（1） Doping ions content has great influences on the crystal phase and crystal size of TiO2. All TiO2 catalysts calcined at 500℃were of anatase phase, and no iron-containing phases was detected. Doping metal ions inhibited the TiO2 grain growth in varying degrees when the dopants in appropriate content. Compared with that of even doped samples which were in the same concentration,the crystal size of composite samples had been little change.（2） BET results indicated the presence of mesoporous structures for all samples prepared. The BET surface areas of uneven doped samples in plan B were bigger than that of even doped samples.But there weren’t apparent change with the increase of the coating times.（3） Although the doping modes were different, the change content of doping ions and amount of metal-doped TiO2 dopants caused different shift of the absorption edge for the incoming light.But as the increase of the coating times, a slight blue shift in the band-gap transition to shorter wavelengths.（4） Photoluminescence spectra of catalysts exhibited great decrease in emission intensity of even doped samples compared with undoped TiO2. Moreover, although the doping modes were different, no new luminescence was occurred because the location of main emission peaks for all Fe-TiO2 were almost the same.（5） While TiO2 was modified in even doping mode, there were different optimal doping amount to different ions, but the effect of modification was not obvious, or even worse than that before. The reason is when the metal ions were uniformly doped, they would increase of the electron-hole pair separation efficiency, but in the same time they would become recombination centers of the electron-hole pairs.（6） While TiO2 was coated one times with 0.5ml water added （equivalent to stoichiometric value） modified in uneven doping mode in plan A exhibited much higher photocatalytic activity , 1-0.02%Fe-TiO2/C-A had the best photocatalytic activity whose apparent rate constant was about 2.73 times as large as that of undoped TiO2, and about 2.08 times as large as that of 0.016%Fe-TiO2 doped by Fe evenly with the same iron content in the whole iron-doped titania particles.（7） While TiO2 modified in uneven doping mode in plan B, were shown to have much higher photocatlytic destruction rate than that of Fe3+-doped TiO2 in even doping mode and undoped TiO2 when doping ion content of supports were above 0.02%.The photocatalytic activity of CCS-derived Fe3+-doped TiO2 were enhanced with the increase of the coating times. 3-0.04%Fe-TiO2/C had the best photocatalytic activity whose apparent rate constant was about 5.32 times as large as that of undoped TiO2, and about 4.58 times as large as that of TiO2 doped by Fe evenly with the same iron content in the whole iron-doped titania particles.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
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