Synthesis and characterization of TiO2 doping with rare earths by sol–gel method: photocatalytic activity for phenol degradation

The enhancement of TiO 2 photocatalyst activity will lead to more practical applications of this technology. In this work we studied the effect of rare earth doping of sol–gel synthesized TiO 2 for phenol degradation and we compared the performance with commercial catalyst. Photocatalysts were characterized by nitrogen adsorption to determine textural properties, ultraviolet visible light diffuse reflectance spectrometry (UV-Vis DRS), X-ray diffraction, STEM-EDS (scanning transmission electronic microscopy-energy dispersive X-ray spectroscopy) and XPS (X-ray photoelectron spectroscopy). Main phase for materials calcined at 500 °C was anatase. Residual nitrogen from NH 4 OH used in the sol–gel synthesis was identified by XPS analysis. Ti 3+ /Ti 4+ ratio increased when TiO 2 was doped with 0.5 wt% of Ce. Anatase phase was stabilized in photocatalysts doped with La even after calcination at 800 °C, for Pr and Nd a mixture of anatase-rutile phases was obtained, whereas for Ce doping only rutile phase was found. For the photocatalytic oxidation of phenol, the best results were obtained for Ce doped TiO 2 , which could be related to the ability of Ce IV /Ce III oxidation/reduction cycle.