Xia Wei, Mei Bastian, Sánchez Miguel D, Strunk Jennifer, Muhler Martin
Laboratory of Industrial Chemistry, Ruhr-University Bochum, 44780 Bochum, Germany.
J Nanosci Nanotechnol. 2011 Sep;11(9):8152-7. doi: 10.1166/jnn.2011.5107.
TiO2 was deposited on high surface area porous silica gel (400 m2g(-1)) in a fluidized bed reactor. Chemical vapor deposition was employed for the coating under vacuum conditions with TiCl4 as precursor. Nitrogen physisorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis spectroscopy were applied to characterize the obtained TiO2-SiO2 composites with different Ti loadings up to 5 wt%. Only a slight decrease in the specific surface area was detected at low Ti loadings. At a Ti loading of 2 wt%, TiO2 was found to be highly dispersed on the SiO2 surface likely in form of a thin film. At higher Ti loadings, two weak reflections corresponding to anatase TiO2 were observed in the diffraction patterns indicating the presence of crystalline bulk TiO2. High resolution XPS clearly distinguished two types of Ti species, i.e., Ti-O-Si at the interface and Ti-O-Ti in bulk TiO2. The presence of polymeric TiOx species at low Ti loadings was confirmed by a blue shift in the UV-vis spectra as compared to bulk TiO2. All these results point to a strong interaction between the TiO2 deposit and the porous SiO2 substrate especially at low Ti loadings.
二氧化钛在流化床反应器中沉积于高比表面积的多孔硅胶（400 m2g(-1)）上。采用化学气相沉积法，在真空条件下以四氯化钛为前驱体进行涂层制备。运用氮气物理吸附、X射线衍射、透射电子显微镜、X射线光电子能谱和紫外可见光谱对所获得的不同钛负载量（最高达5 wt%）的TiO2-SiO2复合材料进行表征。在低钛负载量时，仅检测到比表面积略有下降。在钛负载量为2 wt%时，发现TiO2很可能以薄膜形式高度分散在SiO2表面。在较高钛负载量时，在衍射图谱中观察到对应锐钛矿型TiO2的两个弱反射峰，表明存在结晶态的块状TiO2。高分辨率XPS清晰地区分了两种类型的钛物种，即界面处的Ti-O-Si和块状TiO2中的Ti-O-Ti。与块状TiO2相比，紫外可见光谱中的蓝移证实了在低钛负载量时存在聚合态的TiOx物种。所有这些结果表明，尤其是在低钛负载量时，TiO2沉积物与多孔SiO2基底之间存在强烈的相互作用。
