0000000000147665
AUTHOR
Renzo Campostrini
Sol-gel derived anatase TiO2: morphology and photoactivity
Abstract High-surface area TiO 2 (anatase) was prepared by the sol-gel method and characterized by various instrumental and analytical methods, including X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, porosimetry, specific surface area measurements, scanning electron microscopy, and titration of surface hydroxyl groups. The specimen was tested for photodegradation of phenol and nitrophenols carried out in aqueous suspension at pH = 3; photoactivity was compared with that of commercially available anatase TiO 2 . Results are discussed in terms of porosity, surface area, and availability and population of surface OH groups, consequent upon the particular method used for…
Pyrolysis study of sol-gel derived TiO2powders
An amorphous TiO2 gel was obtained by hydrolysing titanium(IV) isopropoxide with a stoichiometric amount of water using SnCl2 as catalyst. In these operative conditions, a TiO2 gel matrix containing a lower fraction of organic residual was obtained with respect to samples prepared by previously modifying the titanium alkoxide precursor with chelating ligands. Dried gel powders were characterized by N2 adsorption analyses, FT-IR and XRD measurements. Thermogravimetric (TG) and differential thermal analysis (DTA) coupled with mass spectrometric (MS) and gas chromatographic (GC) measurements were performed in order to identify the organic products released from TiO2 gel pyrolysis. The Tg-MS se…
Photocatalytic activity of nanocrystalline TiO2 (brookite, rutile and brookite-based) powders prepared by thermohydrolysis of TiCl4 in aqueous chloride solutions
Abstract Nanocrystalline TiO2 powders were synthesized by thermohydrolysis of TiCl4 in HCl or NaCl aqueous solutions. Rutile, mixtures of brookite and rutile or mixtures of anatase, brookite and rutile were obtained depending on the acidity of the medium. Crystalline phases and composition of the mixtures were identified by using XRD analysis. Pure brookite nanoparticles, separated from the mixtures of brookite and rutile by simple peptization with water, were stable against transformation to rutile up to 750 °C. The prepared TiO2 powders were characterized by thermal analysis, diffuse reflectance spectroscopy and BET surface area determinations. The band gap of bulky brookite was estimated…