Synthesis and characterisation of Gd3+-doped mesoporous TiO2 materials

Using multi-walled carbon nano-tubes (MWNTs) as the template, Gd3+-doped mesoporous TiO2 (M-TiO2) material was prepared by the homogeneous precipitation-assisted template method. The as-prepared photo-catalysts were characterised using X-ray diffraction, scanning electron microscopy, nitrogen adsorption/desorption and ultraviolet-visible (UV-vis) diffuse-reflection spectroscopy analyses. The photo-catalytic properties of Gd3+-doped M-TiO2 were primarily investigated by the photo-degradation of methyl orange under Xe-lamp irradiation and compared with those of pure M-TiO2 and the commercial photo-catalyst Degussa P25. The results showed that the as-synthesised samples were of anatase crystalline phase and had red shifts in their UV-vis patterns with different Gd3+-doping concentrations. Gd3+-adding at 0.12 mol% could significantly enhance the photo-catalytic properties of the M-TiO2 material and the rate of photo-degradation of methyl orange reached 97.3% under Xe-lamp irradiation for 150 min.

Research highlights▶ The multi-walled carbon nano-tubes (MWNTs) are used as temple. ▶ M-TiO2 with high surface area is formed, which favours the photo-catalytic activity of M-TiO2. ▶ The substitution or interstitial incorporation of the Gd3+ ion into the TiO2 lattice produces impurity energy levels in band gap and expands its visible-light response. ▶ The growth of Gd3+ in the crystal lattice of TiO2 produces lattice distortion, damages the crystal sites of TiO2 and avoids the probability of recombination of the electron-hole pair.