Sulfated Ce‐doped TiO₂ as visible light driven photocatalyst: Preparation, characterization and promotion effects of Ce doping and sulfation on catalyst performance

Abstract

Sulfated Ce‐doped TiO 2 photocatalysts, with improved visible light photocatalytic activity, are prepared by sol‐gel method and via impregnation with diluted sulfuric acid. The synthesized samples are characterized by means of X‐ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectra (UV–Vis DRS), Fourier transform infrared (FTIR) spectroscopy, temperature‐programmed desorption of ammonia (NH 3 ‐TPD) and X‐ray photoelectron spectroscopy (XPS). To investigate the effect of Ce doping as well as acid sites on the photoactivity of the synthesized photocatalyst, photocatalytic degradation of Rhodamine B in an aqueous solution is used as a probe reaction to evaluate the photocatalytic activity of the as‐prepared samples under visible light irradiation. It reveals that Ce doping can improve the photocatalytic response of TiO 2 to visible light and the presence of Ce 4+ /Ce 3+ redox process facilitates the separation of photo‐generated electrons and holes. In addition, the impregnation can create Lewis acid sites on the obtained catalyst surface. Lewis acid sites on the catalyst surface could increase the amount of adsorbed oxygen (O ad ) and consequently improve the transform efficiency of Ce 3+ to Ce 4+ . Thereafter an increase in the phtocatalytic activity of sulfated Ce‐doped TiO 2 is achieved. The possible mechanism of RhB degradation by sulfated Ce‐doped TiO 2 photocatalyst is preliminarily discussed. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 494–504, 2017