Sm-TiO2光催化剂的制备及可见光下降解亚甲基蓝的研究

Preparation and properties of Sm-TiO_2 photocatalyst for degradation of methylene blue under visible light irradiation

采用溶胶-凝胶法制备了稀土钐掺杂的纳米TiO_2光催化剂(Sm-TiO_2),通过XRD、XPS、UV-Vis-DRS、PL、Nano-sizer纳米粒度分析仪等对Sm-TiO_2样品进行表征和分析,以亚甲基蓝(MB)作为目标降解物,考察了不同掺杂浓度样品对MB的光催化降解效果。结果表明,Sm的替代掺杂引起的晶格畸变促进了金红石相的形成,但晶界及表面的Sm物种抑制了TiO_2从锐钛矿相向金红石相转变,细化了晶粒。适量的Sm掺杂使TiO_2的吸收光谱阈值红移,有效降低了光生电子-空穴对复合率,提高了TiO_2光催化活性。当pH值=2、掺杂量n(Sm)∶n(Ti)=0.006、热处理温度为500℃时,Sm-TiO_2样品在普通日光灯下光催化降解MB的活性最高,其一级表观速率常数较相同条件下纯TiO_2提高了约4倍。

The nano-TiO2 photocatalysts doped Sm was synthesized by sol-gel method and characterized by XRD, XPS, UV-Vis-DRS, PL and nano-sizer nano particle size analyzer, etc. The photocatalytic activity of Sm-TiO2 with different doping dosage was evaluated by their ability to degrade methylene blue （MB） under the irradiation of fluorescent lamp. The results show that lattice strain caused by substitution of Sm promote the forma tion of rutile phase, but Sm species located crystal boundary and surface can restrain the phase transition from anatase to futile and refine grain. Appropriate doping amount of Sm can broaden the absorption region to visible light, inhibit the recombination of photogenerated electron-hole pairs and enhance the photocatalytic activity of TiO2. The photocatalytic activity of the sample at pH= 1.5, molar ratio of n （Sm） ： n （Ti）=0.006 and sintered temperature of 500 ℃ is the best under the irradiation of fluorescent light, the first-order apparent rate constants increased by about 4 times than that of pure TiO2 under the same experimental conditions.