Preparation, characterization and photocatalytic activity of in situ N,S-codoped TiO2 powders

A simple method for preparing highly photoactive nanocrystalline mesoporous N,S-codoped TiO2 powders was developed by hydrolysis of Ti(SO4)(2) in a NH3:H2O solution at room temperature. The as-prepared TiO2 powders were characterized with X-ray diffraction (XRD), Xray photoelectron spectroscopy (XPS), thermalgravimetric and differential thermal analysis (TG-DTA), UV-vis diffuse reflectance spectra, N-2 adsorption-desorption measurements, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The photocatalytic activity was evaluated for the photocatalytic oxidation of acetone and formaldehyde under UV light and daylight irradiation in air, respectively. The results showed that the as-prepared TiO2 Powders exhibited a stronger absorption in the UV-vis light region and a red shift in the band gap transition due to N,S-codoping. The photocatalytic activity of the as-prepared N,S-codoped TiO2 powders at a temperature range of 400-700 degrees C were obviously higher than that of commercial Degussa P25. Especially, the daylight-induced photocatalytic activities of the as-prepared N,Scodoped TiO2 powders were about ten times greater than that of Degussa P25. The high activities of the N,S-codoped TiO2 can be attributed to the results of the synergetic effects of strong absorption in the UV-vis light region, red shift in adsorption edge, good crystallization, large surface area and two phase structures of undoped TiO2 and N,S-codoped TiO2. (c) 2005 Elsevier B.V. All rights reserved.