La掺杂SiO_2/TiO_2纳米粉体的制备及其光催化性能  

Preparation and Photocatalytic Properties of La Doped SiO_2/TiO_2 Nanocomposite Powder

作　　者：李艳廷[1] 孙秀果[1,2] 王育华[1] 司华艳[1] 杨民力[1] 彭政[1] 

机构地区：[1]石家庄铁道大学材料科学与工程学院,河北石家庄050043 [2]河北省交通工程材料重点实验室,河北石家庄050043

出　　处：《稀有金属》2014年第3期392-397,共6页Chinese Journal of Rare Metals

基　　金：河北省自然科学基金项目(B2013210020;E2012210013;E2011210059);国家教育部留学回国人员科研启动基金项目;河北省教育厅项目(2011164);河北省高校重点学科建设项目资助

摘　　要：采用并流中和法制备了La掺杂的SiO2包覆TiO2纳米粒子,利用X射线衍射(XRD),傅立叶交换红外光谱(FT-IR),透射电镜(TEM)及紫外可见光吸收(UV-Vis)光谱对掺杂改性前后样品进行表征。以紫外光照降解甲基橙为测试体系,研究了La掺杂量及煅烧温度对SiO2/TiO2光催化性能的影响,并对其作用机制做了初步的探讨。FT-IR表明在包覆层和纳米TiO2颗粒之间的界面上形成了Ti-O-Si和Ti-OLa键,从而抑制了金红石相的形成,提高了热稳定性,和XRD分析结果一致,掺杂了La的SiO2/TiO2在800℃时金红石相的含量仍然比较低,和120℃时的含量相当;TEM照片显示改性后的TiO2团聚减小,粒度均匀。UV-Vis光谱分析显示La掺杂SiO2/TiO2的光响应范围拓宽至可见光区,其中光吸收红移最大的样品为3.0%La掺杂量的SiO2/TiO2,带隙能(Eg)由原来的2.98 eV降为为2.41 eV。光催化性能实验结果显示当La的摩尔掺杂量为3.0%时,其光催化活性最好,光照20 min,与未掺杂改性的TiO2相比甲基橙的光降解率提高了55.1%;另外,未掺杂TiO2煅烧温度对光催化影响显著,当温度由120℃增加为800℃时,光照25 min的降解率就由69%降为10.7%,而掺La的SiO2/TiO2煅烧温度对其光催化性能影响不大。SiO2/TiO2 nanoparticles doped with the different contents of La were prepared by a flow-together neutralization process and characterized by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FT-IR）, transmission electron microscopy （TEM） and UV-Vis. The effects of La content and calcination temperature on the photocatalytic activity were investigated by the photodegrada- tion of methyl orange under ultraviolet light irradiation. The possible mechanism was also analyzed primarily. The results of FT-IR showed that the Ti - O - Si and Ti - O - La bonds were formed at the interface of the coating layer and TiO2 particles. The presence of La^＋3＋ in SiO2/TiO2 could inhibit the phase transformation from anatase to rutile, and enhance the thermal stability of TiO2. The XRD patterns indicated that the percentage of rutile phase was still very low in La-doped SiO2/TiO2 sample at 800 ℃, which was equal to that at 120 ℃. The TEM images demonstrated that La-doped SiO2/TiO2 nanoparticles had uniform size distribution and polished surface. The absorption spectra indicated an extension of light absorption into the visible light region for the as-prepared samples. Among all the samples, the largest red-shift could be found in La doped SiO/TiO2 sample with 3.0% （mole fraction） La, the band gap reduced from 2.98 to 2.41 eV. The photodegradation results showed that the composite powder with 3.0% La had the best ability of pho- to-degradation. In comparison with pure TiO2 nanoparticles, the photodegradation efficiency could be improved to 55.1% after reaction for 20 rain. In addition, the effect of calcination temperature on the photocatalytic activity of undoped TiO2 was obvious, the photodegradation efficiency decreased from 69% to 10. 7% for 25 min with calcination temperature increasing from 120 to 800 ℃. For La-doped SiO/TiO2 sample, the effect of calcination temperature was negligible.

关 键 词：TIO2 La—SiO2 TIO2 光催化降解 稀土 

分 类 号：O643[理学—物理化学]