【作者】 朱幸福；

【导师】 李吉学；

【作者基本信息】 吉林大学 ， 无机化学， 2011， 博士

【摘要】 碳纳米管是一种优异的一维纳米材料,具有独特的结构及物理化学特性,被认为是最具有未来应用前景的新材料之一。其中,以碳纳米管材料为基体的纳米复合材料,由于可以充分发挥碳纳米管和与其复合纳米材料的优点逐渐引起研究人员广泛的关注。本文报道了利用碳纳米管作为载体分别制备出了Ni/CNT,空心CoO/CNT, Si/CNT, TiO2/CNT纳米复合材料。以碳纳米管为模板制备出了SnO2/TiO2, SnO2/SiO2复合纳米管材料。并且对所制备的纳米复合材料的结构,形貌和性质进行了研究和表征。其主要内容如下：1.对基底增强无电镀沉积法进行了改进,利用此法制备出了纳米Ni/CNT复合材料,并且可通过改变NiSO4溶液的浓度而控制Ni纳米粒子的大小此外,在尝试利用基底增强无电镀沉积法制备Co/CNT复合材料时,我们发现由于柯克达尔效应Co/CNT中的Co纳米粒子转变成空心结构的CoO/CNT复合材料。研究探索利用低温镁热还原法制备Si/CNT复合材料的新路线,发现可以通过控制SiO2/CNT前驱体的SiO2层厚度来控制复合材料中Si纳米粒子的大小2.利用两相热法制备出了粒径均一分散均匀的TiO2/CNT复合材料。研究了水油比对TiO2纳米粒子的负载量及反应时间对粒径大小的影响：水油比为1：1时TiO2纳米粒子在碳纳米管上的负载量最多；随着反应时间的增加,TiO2纳米粒子的粒径也随之增加。此外,我们还研究了碳纳米管表面缺陷对TiO2的光催化活性的影响。分别将碳纳米管在浓硝酸中纯化1h,4 h,8 h,12 h以获得具有不同缺陷数量的碳纳米管。碳纳米管表面缺陷数量可以通过XPS测量氧含量进行表征。随着时间的增加,氧含量从约3%增加到8.2%。光催化研究发现,纯化8 h的碳纳米管与TiO2纳米粒子的复合材料具有最高的光催活化性。3.以碳纳米管为模板制备出TiO2及SnO2/TiO2复合纳米管,并利用XRD及SEM, TEM, XPS对其显微结构进行了表征。对SnO2/TiO2复合纳米管进行光致发光谱及表面光电压谱的分析测试表明SnO2纳米粒子的复合可以使TiO2纳米管的光生电子-空穴对有效的分离。SnO2/TiO2纳米管表现出了比商业TiO2的P25更强的光催化活性,有望应用于光催化降解污染物领域。4.以碳纳米管为模板制备出SnO2/SiO2(in)及SnO2/SiO2(out)两种复合纳米管材料。这两种复合材料都具有窄粒径分布,大比表面积及好的热稳定性。对SnO2/SiO2复合纳米管进行紫外-可见光吸收光谱测试表明,SiO2壳的限制作用使SnO2纳米粒子具有很小的粒径,由于量子尺寸效应引起了吸收谱带的蓝移。我们对SnO2/SiO2(in)及SnO2/SiO2(out)两种复合纳米管材料进行了光催化降解反应研究。结果表明SnO2/SiO2(in)复合纳米管具有和商业P25相同程度的光催化活性。更多还原

【Abstract】 As an excellent 1D nanomaterial. carbon nanotubes (CNTs) with an unique structure and chem-physical properties have been widely applied in various areas. Among them, carbon nanotube composites have attracted increasing interest because of the combination of the CNTs and other materials may lead to a successful integration of the properties of the components in the new hybrid materials. In our work, a series of carbon nanotube composites such as Ni/CNT, hollow CoO/CNT, Si/CNT and TiO2/CNT have been prepared using carbon nanotubes as supports. Moreover, the SnO2/TiO2, SnO2/SiO2 composite nanotubes have also been fabricated using carbon nanotubes as templates. Furthermore, the structure, morphology and properties of these composite materials have been characterized and studied. The research contents as followed:1. The modified substrate enhanced electroless deposition (SEED) process was used for preparing the Ni/CNT composites. The size of the Ni NPs can be controlled by varying the concentration of the NiSO4 solution. Moreover, we found that the Co/CNT composites converted into hollow CoO/CNT composites due to the Kirkendall effect when we tried to prepare the Co/CNT composites by the modified SEED process. A new route for the synthesis of Si/CNT composites by a low-temperature magnesiothermic reduction process was presented. Moreover, the size of the Si NPs could be controlled by varying the silica (SiO2) thickness of SiO2/CNT precursors.2. A two-phase thermal approach was used to prepare the TiO2/CNT composites which have TiO2 nanoparticles with a narrow size distribution and a uniform dispersion on the CNT surface. We studied the influence of the ratio of water and oil on the amount of the TiO2 NPs load on the CNTs and the reaction time on the size of the TiO2 NPs. The amount of TiO2 NPs loaded on the CNTs decreased no matter the water content either too much or too little. The size of the TiO2 NPs increased with the increase of reaction time. In addition, we also investigated the influence of the CNTs surface defect on the photo-catalytic activity. In order to get the CNTs with the different number of defect, we treated the CNTs with the concentrated nitric acid for 1 h,4 h,8 h and 12 h. respectively. The number of defects was determined by XPS to measure the oxygen content of the CNTs. The oxygen content increased from raw 1.25% to 8.2% with increasing the acid-treatment time. The composite prepared with the TiO2 and the CNTs (8 h) has the best photo-catalytic activity.3. The TiO2 nanotubes and SnO2/TiO2 nanotubes were prepared using CNTs as templates. The structural and morphological characterizations of the TiO2 nanotubes and SnO2/TiO2 nanotubes have been carried out using XRD, SEM, TEM and XPS. The PL spectra and X-ray photoelectron spectroscopy (XPS) method indicated that the separation rate of photo-induced electron-hole pairs was improved through SnO2 NPs combined with the TiO2 nanotubes. The SnO2/TiO2 nanotubes have a higher photo-catalytic activity than P25. suggesting that it would be promising as a new photo-catalytic material in the photo-catalysis area.4. The two kinds of composite nanotubes. SnO2/SiO2(in) and SnO2/SiO2(out), were synthesized using CNTs as templates. They all possessed a narrow size distribution, a large specific surface area, and good thermal stability. UV-visible absorption spectra of the SnO2/SiO2 composites present a blue-shift with the decrease of particle size, which could be attributed to the quantum size effect. The photo-catalytic reaction showed that the ) has the same photo-catalytic ability as the P25.更多还原