摘要
以葡萄糖、氟钛酸铵和氟硅酸铵为原料,采用一锅水热合成法在葡萄糖聚合形成的胶体碳球表面原位生成了含有Ti/Si物种的前驱物实心微球,再经高温焙烧脱除碳球模板,制得Si掺杂的TiO2空心微球.应用高分辨透射电镜、X射线衍射、X射线光电子能谱和N2吸附-脱附等手段对样品进行了表征.结果表明,Si进入到TiO2的晶格,形成的Si–O–Ti键不仅可有效抑制TiO2物相从锐钛矿向金红石转变,而且还能阻碍TiO2纳米晶在焙烧过程中快速长大.随着Si掺杂量的增加,组成空心微球壳层的TiO2纳米晶的平均晶粒度逐渐减小,而空心微球的比表面积和孔体积逐渐增大.以亚甲基蓝(MB)溶液为模拟污染物,考察了紫外光下Si掺杂TiO2空心微球的光催化性能.结果表明,随着Si掺杂量的增加,TiO2空心微球对MB溶液的降解效率显著升高;当Si的摩尔分数为0.5时,空心微球的光催化效率最高,是P25的1.25倍.
Solid precursory microspheres composed of Ti/Si species were in situ formed on the surface of a colloid carbon microsphere template derived from glucose polymerization and carbonization by a one-pot hydrothermal method using ammonium fluorotitanate,ammonium fluorosilicate,and glucose as source materials. Si-doped TiO2 hollow microspheres were then obtained after calcination and removal of the carbon microsphere template at high temperature. High-resolution transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,and N2 adsorption-desorption were used to characterize the samples. The effect of Si doping on the microstructure and photocatalytic performance of the TiO2 hollow microspheres was investigated. The results confirmed that the Si element entered into the lattice of TiO2 and formed Si–O–Ti bond,which could not only effectively suppress the phase transformation from anatase to rutile,but also restrain the rapid growth of TiO2 nanocrystallites during the calcination process. The average grain size of the nanocrystallites constituting the shell of the microspheres decreased gradually and the specific surface area and pore volume of the hollow microspheres increased progressively with the increase in the amount of Si doping. The photocatalytic activity of the Si-doped TiO2 hollow microspheres was measured under ultraviolet light using methylene blue solution as a simulated degradation model. The results demonstrated that the degradation efficiency of TiO2 hollow microspheres enhanced gradually with increasing Si doping in its mol fraction range of 0–0.5. Especially,the degradation efficiency of TiO2 hollow microspheres is 1.25 times that of P25 when the Si mol fraction is 0.5.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
2011年第2期286-292,共7页
基金
国家自然科学基金(50474071)
关键词
硅掺杂
二氧化钛
碳球模板
水热合成
空心微球
光催化
silicon doping
titania
carbon microsphere template
hydrothermal synthesis
hollow microsphere
photocatalysis
