Preparation and characterization of Rb-doped TiO2 powders for photocatalytic applications

TiO2 nanoparticles doped with different concentrations of Rb were prepared by sol–gel method. The crystal structures of samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was confirmed by the Rietveld refinement method that the as-prepared samples crystallize in anatase phase and Rb doping induces expansion and distortion of the crystal lattice. Compared with the pure TiO2, the Rb-doped nanoparticles have smaller crystal size and better dispersibility. Degradation rate of methylene blue was used to evaluate the photocatalytic activity of Rb–TiO2. It indicated that doping Rb into TiO2 can effectively improve the photocatalytic activity of TiO2 and the mechanisms were discussed in detail. When using the sample doped with 0.20% Rb, methylene blue degraded with the fastest rate (97% within 60 min).