Preparation and photoactivity of nanostructured TiO2 particles obtained by hydrolysis of TiCl4

This work reports the preparation of nanostructured polycrystalline TiO2 photocatalysts obtained by hydrolysis of TiCl4 in very mild conditions. Several samples were prepared as suspensions or colloidal dispersions by using TiCl4/H2O volume ratios ranging between 1:1 and 1:100. The samples were characterised by X-ray diffraction analysis, specific surface area determination, diffuse reflectance spectroscopy and scanning electron microscopy. 4-Nitrophenol photodegradation was used as probe reaction to test the photoactivity of the catalysts. Some samples revealed a photoactivity higher than that of Degussa P25 in similar experimental conditions and the most photoactive one was that prepared by using the TiCl 4/H2O volume ratio equal to 1:50. A dialysis process was performed in some cases to reduce the amount of chloride ions present in the system. The presence of Cl- ions appeared to be dramatically detrimental for Degussa P25 while a lower influence was found for the home prepared samples.