Influence of annealing temperature on structural, optical and photocatalytic properties of TiO<inf>2</inf>-CeO<inf>2</inf> nanopowders

Abstract

TiO2-CeO2 nanopowders were synthesised by a ball-milling process and then annealed at temperatures from 500° to 800 °C. X-ray diffraction and diffuse reflectance spectra were used in combination with temperature programmed desorption to determine the structural and microstructural changes of nanopowders as a the function of annealing temperature. The results of the X-ray analysis showed that the weight fraction of the cerianite phase remained unchanged with a temperature rise of 600–700 °C, indicating that the phase changes occur only within TiO2. The TiO2-CeO2 nanopowder showed enhanced optical properties with a red shift after the thermal treatment. Photocatalytic studies revealed that the sample annealed at 600 °C showed higher photocatalytic activity than samples annealed at lower or higher temperatures in the degradation of the methyl orange. The activity test of all samples is in accordance with photoluminescence measurements, proportional to the concentrations of hydroxyl radicals at the photocatalyst surfaces.