多孔SnO₂、ZnO纳米材料及PPy/F-MWCNTs复合纳米材料的制备及其气敏性能研究

【作者】 王志敏；

【导师】 唐新村；

【作者基本信息】 中南大学 ， 有机化学， 2011， 硕士

【摘要】 纳米材料及纳米技术的发展为改善传感器的性能提供了新的发展机会。近年来,具有多孔结构的金属氧化物半导体(MOS)纳米材料与碳纳米管(CNTs)基纳米复合材料因其优异的性能而倍受关注。因此制备多孔结构MOS纳米材料及CNTs基纳米复合材料对改善气敏传感器的性能具有很重要的意义。(1)通过原位化学氧化聚合法成功制备了聚吡咯(PPy)包裹酸处理多壁碳米管(F-MWCNTs)的复合材料(PPy/F-MWCNTs)。对所制备的PPy/F-MWCNTs纳米复合材料,分别采用傅里叶变换红外光谱分析(FT-IR)、紫外可见漫反射(UV-vis DRS)、热重分析(TGA)、X-射线衍射(XRD)、比表面分析(BET)、场发射扫描电镜(FE-SEM)口透射电镜(TEM)进行表征。实验结果表明在F-MWCNTs表面均匀包覆了一层约25-40 nm厚的PPy, PPy/F-MWCNTs的比表面积较单一的PPy提高了近3倍。基于PPy/F-MWCNTs的气敏元件在室温下对NH3的气敏性能较单一聚吡咯和碳纳米管具有更高的灵敏度,更短的响应时间以及更好的稳定性,其中对200 ppm NH3的灵敏度能达到1.9,响应时间为135s.另外与PPy包覆未经酸处理的MWCNTs相比PPy/F-MWCNTs的灵敏度更高。(2)通过高温处理层状碱式碳酸锌前躯体的方法成功制备了多孔ZnO单晶纳米片。前躯体碱式碳酸锌(LBZC)采用聚乙烯吡咯烷酮(PVP)为表面活性剂,尿素水溶液水热的条件下制备。所得多孔ZnO单晶纳米片分别采用X-射线衍射(XRD),傅里叶转换红外光谱分析(FT-IR),热重-示差分析(TGA-DSC),场发射扫描电镜(FE-SEM),透射电镜(TEM),选区电子衍射(SAED),比表面分析(BET)等进行表征。实验结果表明所制备的多孔ZnO单晶纳米片直径大约几百个纳米,厚度约为15 nm。基于该多孔ZnO单晶纳米片的气敏传感器在300℃下对乙醇具有很好的灵敏度,比较高的选择性以及快速的响应-恢复性能,是一种很好的气敏材料。而且,这种溶液法也可以用来制备其他具有均一形貌的金属氧化物多孔材料。(3)采用一种简单的溶剂热-高温处理的方法成功制备了由大量15.9 nm左右的单晶SnO2微纳米球组装而成的分级结构多孔SnO2纳米棒。采用X-射线衍射(XRD),傅立叶转换红外光谱分析(FT-IR),热重-差热分析(TGA-DTA),场发射扫描电镜(FE-SEM),透射电镜(TEM),选区电子衍射(SAED),比表面分析(BET)等测试手段对样品的形貌与结构进行表征。实验结果表明多孔SnO：纳米棒长度约5-6μm,基于该结构材料的气敏元件在240℃下对乙醇蒸气具有非常好的灵敏度,快速的响应-恢复时间以及比较好的选择性及稳定性。更多还原

【Abstract】 In the past few years, the development of nanomaterials and nanotechnologies provided new opportunities for improving the properties of gas sensors. Recently, the sensing properties of porous MOS nanostructured materials and CNTs-based nanocomposites have been widely studied, owing to the great surface activity provided by their enormous surface areas for chemical reaction and effective diffusion of gases into the materials. Hence, the preparation of porous MOS nanomaterials and CNTs-based nanocomposites would be of significance for improving the gas sensor’s performance. In view of this problems, this paper mainly do the following work:(1) A nanocomposite(PPy/F-MWCNTs) has been successfully synthesized by the in-situ chemical oxidation polymerization with acid-treated multi-walled carbon nanotubes(F-MWCNTs) and polypyrroles(PPy). The asprepared composiste was characterized by Fourier transformed infrared spectra (FT-IR), UV-vis diffuse reflection spectroscopy(UV-vis DRS), Thermal gravimetric analysis(TGA), X-ray diffraction study(XRD), Branauer-Emmett-Teller analysis(BET), Field-emission scanning electron microscopy(FE-SEM) and Transmission electron microscopy (TEM). The results has revealed that the F-MWCNTs was well-coated with about 25-40 nm thickness of polypyrrole, and the surface specific areas of PPy/F-MWCNTs is about three times than that of pure PPy. The sensors fabricated by PPy/F-MWCNTs exhibited a higher sensitivity, better response/reproduc-ibility towards NH3 vapor at room temperature than by pure PPy or F-MWCNTs. The sensitivity was 1.9 even to 200 ppm of NH3 and the response time was 135s. In addition, compared with MWCNTs untreated with acid, the as-prepared PPy/F-MWCNTs also exhibits higher sensitivity than that prepared without acid-treated MWCNTs.(2) In this paper, the porous single-crystalline Zinc oxide (ZnO) nanoplates were fabricated from the thermal-decomposition of layered basic zinc carbonate (LBZC) precursors, which were synthesized by an urea hydrothermal method used PVP as surfactant in the solution of water. The structure and morphology of the as-synthesized samples were characterized by means of X-ray powder diffraction(XRD), Fourier transform infrared(FT-IR), Thermogravimetric-differential scanning calorimetry analysis(TGA-DSC), Field-emission scanning electron microscopy(FE-SEM), Transmission electron microscopy(TEM), Selected area electron diffraction (SAED) pattern and Nitrogen adsorption-desorption isotherm analysis. The results showed that the average diameter of as-prepared porous ZnO nanoplates were about several hundred nanometers and the thickness of the nanoplates was about 15 nm. The sensors fabricated from the porous ZnO nanoplates exhibited good sensitivity, high selectivity, rapid response-recovery times to ethanol vapors at 300℃and would be good candidate for gas sensing materials.Moreover, it is believed that the solution-based approach could be extended to fabricate other porous metal oxide materials with a unique morphology.(3) Hierarchical porous Tin oxide (SnO2) nanorods that composed of numerous single-crystalline SnO2 nanoparticles with about 15.9 nm in diameter were synthesized by a facile hydrothermal method with the help of the surfactant DMF followed by calcination in air atmosphere.The structure and morphology of resulting samples were characterized by means of X-ray powder diffraction (XRD), Fourier transform infrared(FT-IR), Thermogravimetric-differential thermalgravimetric analysis(TGA-DTA), Feld-emission scanning electron, Transmission electron microscopy(TEM), selected area electron diffraction (SAED) pattern and Branauer-Emmett-Teller analysis. The results showed that the as-synthesized porous nanorods were about 5-6μm in length. The sensors fabricated from the porous SnO2 nanorods exhibited good sensitivity, high selectivity, long-term stability and rapid response-recovery times to ethanol vapors at 240℃.更多还原