Abstract:

Potassium titanate (KTO) nanobars were synthesized by a hydrothermal method and used as a precursor to synthesize TiO₂ nanocrystals. La doping of the TiO₂ nanocrystals was achieved by introducing La³⁺ into the hydrothermal media. The hydrothermal transition of KTO to TiO₂ was investigated under various conditions,finding that the pH of the hydrothermal media, the temperature, and the pre-treating procedure play important roles in the phase transition. X-ray diffraction and transmission electron microscopywere used to characterize the crystal phase and morphology of the samples and the transition process of the hydrothermal reaction. The content of La³⁺ in the samples was measured by inductively coupled plasma atomic emission spectroscopy. The photocatalytic activity of the La-doped TiO₂(LaT) was measured under UV light with the degradation of methyl orange (MO, 10 mg/L).The results showed that the photocatalytic activity of TiO₂ was enhanced remarkably by La-doping. LaT hydrothermally prepared with 0.15 mol/L La³⁺at under 180℃ showedthe optimal reaction constant of 0.11 min^-1 for the degradation of MO, about 9.20 and 3.69 times than those of bare TiO₂ and P25, respectively.

Key words: Potassium octatitanate, Phase transition, La-doped titania, Photocatalytic activity, Hydrothermal synthesis