Wenjie Zhang

Calcination Conditions on the Properties of Porous TiO2 Film

Porous TiO2 films were deposited on SiO2 precoated glass-slides by sol-gel method using PEG1000 as template. The strongest XRD diffraction peak at 2θxa0=xa025.3° is attributed to [101] plane of anatase TiO2 in the film. The increases of calcination temperature and time lead to stronger diffraction peak intensity. High transmittance and blue shift of light absorption edge are the properties of the film prepared at high calcination temperature. The average pore size of the films increases with the increasing calcination temperature as the result of TiO2 crystalline particles growing up and aggregation, accompanied with higher specific surface area. Photocatalytic activity of porous TiO2 films increases with the increasing calcination temperature. The light absorption edge of the films slightly moves to longer wavelength region along with the increasing calcination time. The mesoporous film calcinated at 500xa0°C for 2xa0h has the highest transmittance, the maximum surface area, and the maximum total pore volume. Consequently, the optimum degradation activity is achieved on the porous TiO2 film calcinated at 500xa0°C for 2xa0h.

Properties of In-TiO2 Photocatalyst as the Factors of Indium Doping Content and Calcination Temperature

Abstract In-doped TiO2 photocatalysts were prepared using sol-gel method in order to investigate the effects of indium doping content and calcination temperature on structural and photocatalytic activity of the materials. Powder X- ray diffraction (XRD), scanning electron microscope (SEM), FT-IR, X-ray photoelectron spectroscopy (XPS), and N2 adsorption-desorption were employed to analyze the materials. XRD peaks of In-doped TiO2 materials are well corresponding to the diffraction peaks of anatase TiO2 phase. In3+ ions incorporate into the TiO2 crystal lattice by substituting Ti4+, leading to lattice cell expansion. The specific surface area of In-TiO2 increases with the increase of In content up to 3%, due to restrained crystal growing after In doping. Photocatalytic activity of In-doped TiO2 material shows strong dependence on In content. The 3%In-TiO2 sample presents the maximal photocatalytic activity. The increasing average pore size along with increasing calcination temperature indicates collapse of porous structure in the material. The initial 10 mg/L methyl orange can be completely decolorized after 70 min of UV irradiation on the 3%In-TiO2 sample calcinated at 400 °C, which is much better than 62.3% decoloration of the dye on pure TiO2. Methyl orange decoloration efficiency decreases from 100% to 77.9% on 3%In-TiO2 after 6 reaction cycles, showing satisfactory reusability of In-doped TiO2.

Role of cetyltrimethyl ammonium bromide on sol–gel preparation of porous cerium titanate photocatalyst

AbstractCetyltrimethyl ammonium bromide (CTAB) was used as template agent to prepare porous cerium titanate by sol–gel method. Besides major brannerite CeTi2O6 in monoclinic system, the addition of CTAB template leads to formation of minor anatase TiO2 and CeO2 phases. FT-Far-IR spectra also prove Ce-O and Ti-O-Ti bonds in the porous cerium titanate. The addition of CTAB template in the precursor can obviously enlarge BET surface area and pore volume of cerium titanate. Removal of CTAB template during calcination leaves mesoporous structure in the cerium titanate samples, which are presented in the N2 adsorption-desorption isotherms. Not only more hydroxyl radicals can be produced on the samples obtained using CTAB, but also photocatalytic oxidation efficiency is strongly influenced by the variation of CTAB amount. The reaction rate constant is 2.44u2009×u200910−2u2009min-1 on the porous cerium titanate sample obtained using 2u2009g CTAB, while the reaction rate constant is only 9.60u2009×u200910−3u2009min-1 on the sample without CTAB. UV-Visible spectra of ofloxacin solution during photocatalytic oxidation demonstrate the degradation of typical organic groups in ofloxacin molecule.n CTAB was used as template agent to prepare porous cerium titanate by sol–gel method. CTAB can introduce porous structure and enhance surface area of the samples. More hydroxyl radicals can be produced on the samples using CTAB as template. Photocatalytic oxidation efficiency is strongly affected by the variation of CTAB dosage.HighlightsCTAB was used as template agent to prepare porous cerium titanate by sol–gel method.CTAB can introduce porous structure and enhance surface area of cerium titanate.The addition of CTAB may cause production of TiO2 and CeO2.More hydroxyl radicals can be produced on the samples using CTAB as template.Photocatalytic oxidation efficiency is strongly affected by the variation of CTAB dosage.