Preparation and photoactivity of nanocrystalline TiO2 powders obtained by thermohydrolysis of TiOSO4

Nanocrystalline TiO2 photocatalysts were synthesizedin mild conditions by thermohydrolysis of TiOSO4in water at 100 C and post-calcination treatment at varioustemperatures. The TiO2 powders were characterized byX-ray diffraction, X-ray photoelectron spectroscopy, specificsurface area determinations, scanning electronmicroscopy and electron paramagnetic resonance measurements.The photoactivity of the samples was testedemploying the photodegradation of 4-nitrophenol inliquid–solid regimen and the photooxidation of gaseous2-propanol. The best results were obtained with the powdercalcined at 600 C for 10 h. Surprisingly, the not calcinedsample was the most active for the abatement of NOx underirradiation.