Influence of Re and Ru doping on the structural, optical and photocatalytic properties of nanocrystalline TiO2

TiO2 and TM-doped TiO2 (TM = Re, Ru) anatase crystalline nanopowders were synthesized by a simple hydrothermal method. Samples with nominal TM/Ti ratio of 0.01 were prepared for this study. Their structural, microstructural and optical properties were studied. The lattice parameters of the different prepared samples were calculated and their mean crystallite sizes determined to be in the range 15-7 nm, the lower values being obtained for the doped crystallites. The samples' specific surface areas were determined and correlated with their mean crystallite sizes. The incorporation of the dopant elements results in an increase of the optical absorption in the visible range. The samples' optical bandgap and Urbach energies were calculated from UV-Vis diffuse reflectance spectra. The photocatalytic behavior of the synthesized samples was investigated for the rhodamine B and phenol degradation processes, the kinetics of the different photo-oxidation reactions being also studied. The results showed that doping either with Re or Ru can lead to enhancement of the TiO2 photocatalytic efficiency and that, among the synthesized samples Ru-doped TiO2 is the most efficient photocatalyst for both the Rhodamine B and phenol photodegradation reactions.