水热法制备具有高光催化活性的镧掺杂二氧化钛纳米晶

采用水热法合成钛酸钾(K₂Ti₈O₁₇)纳米棒,并将它作为前驱体水热转晶合成TiO₂纳米晶,同时通过在水热体系中引入稀土元素La³⁺实现对TiO₂的La掺杂.考察了不同条件下钛酸盐向TiO₂的转晶过程,发现水热溶液的pH值、温度以及预处理步骤对转晶过程有很大的影响.利用X射线衍射以及透射电子显微镜对样品的晶相和形貌进行了表征.利用电感耦合等离子体原子发射光谱测量了所合成的La掺杂TiO₂样品中的La含量.通过在紫外光下降解甲基橙(MO,10mg/L)测试了La掺杂TiO₂样品的光催化性能.结果表明La掺杂后TiO₂的光催化活性大大提高.在0.15mol/LLa³⁺浓度下180oC水热合成的La掺杂TiO₂样品显示了最佳的光催化活性.其对MO的光催化降解反应常数高达0.11min^-1,大约是空白TiO₂样品的9.20倍,P25TiO₂的3.69倍.

La-doped titaniananocrystals with superior photocatalytic activity prepared by hydrothermal method

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.