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

Abstract

The enhancement of TiO2 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 TiO2 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 NH4OH used in the sol–gel synthesis was identified by XPS analysis. Ti3+/Ti4+ ratio increased when TiO2 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 TiO2, which could be related to the ability of CeIV/CeIII oxidation/reduction cycle.