【作者】 吴康兵；

【导师】 胡胜水；

【作者基本信息】 武汉大学 ， 分析化学， 2004， 博士

【摘要】 碳纳米管是由片层的石墨卷成的无缝中空的纳米级同轴圆柱体，圆柱体两端各有一个由半个富勒烯球体分子形成的帽子，它的直径可以从几个埃到几十纳米，而长度却可达到几个毫米。碳纳米管可分为由一层石墨组成的单壁碳纳米管(single-walled carbon nanotube,SWNT)和由多层石墨组成的多壁碳纳米管(multi-walled carbon nanotube,MWNT)两种。自1991年Iijima首次发现以来，碳纳米管由于具有奇特的结构、电学、机械、电化学性能以及在材料领域的巨大潜力而受到世界的广泛关注，开辟了材料科学和纳米技术的一个新时代。目前，碳纳米管已经广泛地应用于物理、化学、能源、材料等众多领域。 任何事物都有它的两面性，碳纳米管也不例外。它虽然具有上述种种优点，但由于碳纳米管的巨大分子量导致了其不可溶解性，这极大地制约了它在制备电化学传感器方面的应用。碳纳米管电化学传感器(或者碳纳米管化学修饰电极)的制备是一项极富挑战性的研究课题，对拓宽碳纳米管的应用范围，丰富化学修饰电极的制备途径具有深远的意义。 本论文以碳纳米管为修饰材料，探索新颖的碳纳米管分散体系和成膜技术，研究和制备出几类新型的碳纳米管膜修饰电极。这不仅大大拓展了碳纳米管的应用范围，而且丰富和发展了电化学分析的内容、技术和理论。结合各种表征手段，对所制备的碳纳米管膜修饰电极进行了较全面的表征，并重点开展了所制备的碳纳米管膜修饰电极在电分析化学中的应用基础研究。本论文的研究内容主要包括： 第一部分：多壁碳纳米管—Nafion复合膜修饰电极的研究 选择Nafion作为多壁碳纳米管(MWNT)的分散剂，将多壁碳纳米管有效地分散在Nafion-无水乙醇中，该MWNT—Nafion分散液性质稳定，通过溶剂挥发制备出MWNT-Nafion复合膜修饰电极。用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、反射红外光谱技术、以及电化学技术对该化学修饰电极进行了表征。实验发现，MWNT—Nafion膜修饰电极对多巴胺的电化学氧化还原具有明显的催化特性和抗干扰能力，它不仅可以提高多巴胺的氧化还原峰电流，而且降低了多巴胺的氧化还原过电位，同时实现了在高浓度抗坏血酸和尿酸存在下多巴胺的选择性测定。第二部分:碳纳米管一表面活性剂复合膜修饰电极的研究 表面活性剂在电化学和电分析化学中已得到十分广泛的应用。我们选用了一种双C一H疏水链的表面活性剂(双十六烷基磷酸，DHP)作为碳纳米管的特效分散剂，成功地将碳纳米管分散在水中。此分散体系十分稳定、碳纳米管含量高(可达到lmg/mL)，而且在电极表面具有成膜均匀、稳定、重现性好的特点。 (l)用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、电化学交流阻技术以及循环伏安法对MWNT一DHP膜进行了表征。 (2)利用多壁碳纳米管的结构特性(如中空结构、大的比表面、拓扑缺陷以及强的吸附能力等)，结合I一对铅、福离子的诱导吸附作用，开发出一种高灵敏度同时测定水体中铅、福离子的碳纳米管修饰电极及检测体系。该方法具有灵敏度高、分析速度快、成本低、重现性好等优点，并成功应用于环境水样中铅、隔离子的测定，测定结果与原子吸收测定的结果相一致。 (3)多巴胺(DA)和5一轻色胺(5一HT)是两种十分重要的神经递质，在常规固体电极上由于它们的电化学性质相似，氧化峰相互重叠，通常很难实现二者的同时测定。而且抗坏血酸也产生严重的干扰，三者的氧化峰重叠在一起，形成一个大的氧化峰包。但在MWNT一DHP膜修饰玻碳电极上，DA和5一HT分别在0.18V和0，36V出现两个相互间无干扰、灵敏度高的氧化峰(峰电位之差达180 mV)。与裸玻碳和DHP膜修饰玻碳电极相比，MwNT一DHP膜修饰电极对DA和5一HT的氧化表现出明显的催化活性，为DA和5一HT的氧化提供了较多的反应位点，加速了它们的电子交换速度，显著提高了氧化电流、降低了氧化过电位。进一步研究指出，高浓度的抗坏血酸和尿酸不干扰DA和5一HT的电化学响应。 (4)详细考察了DNA以及鸟嚓吟(G)和腺嗓吟(A)在MWNT一DHP膜电极上的电化学行为，发现MWNT一DHP膜对G和A的氧化表现出催化特性，它不但显著提高了G和A的氧化峰电流，而且还降低了它们的氧化过电位。在此基础上，用计时电量法比较了G和A在裸玻碳电极、DHP膜电极以及MWNT一DHP膜电极上的吸附量，发现G和A在MWNT一DHP膜上的吸附量比其它两种电极提高近一个数量级，正是吸附量的提高导致了G和A在MWNT膜上氧化峰电流的显著增加。 通过对G和A测定条件的优化，建立了一种同时测定G和A的电分析方法，并成功用于双链小牛胸腺DNA中G和A含量的测定，进而得到(G+C)/(A+T)的比值，其结果与理论值很好吻合。 (5)为了进一步考察此修饰电极在电分析中的应用，研究了植物生长激素一叫噪乙酸在此修饰电极上的电化学行为，制备出叫噪乙酸电化学传感器，并成功用于植物中叫垛乙酸的测定。 (6)分别研究了甲状腺素和氯霉素在多壁碳纳米管膜修饰电极上的电化学行为，实验发现MWNT膜显著提高了测定甲状腺素和氯霉素的灵敏度。通过实验条件的优化，建立了两种新的测定甲状腺素和氯?更多还原

【Abstract】 Carbon nanotubes (CNTs) are arrangements of carbon hexagons that are formed into tiny tubes. They usually have a diameter ranging from a few angstrom to tens of nanometers and can have lengths up to several micrometers. There are two distinct types of carbon nanotubes. The so-called single-walled carbon nanotube (i.e., SWNT or graphene tube) is made of one layer of graphene sheet while the multi-walled carbon nanotube (i.e., MWNT or graphitic tube) consists of more than one layer. Since their discovery bv lijima, CNTs have attracted much attention and opened up a new era in material science and nanotechnology due to their fascinating and extraordinary structural, mechanical, electrical, and electrochemical properties as well as their promise in the field of materials science. Now, CNTs have been widely used in various fields such as physics, chemistry, energy and material science.Everything has two sides, and there is no exception for carbon nanotubes. CNTs possess many attractive advantages, but the insolubility of CNTs in almost all solvents limits their application in the fabrication of CNTs-based electrochemical sensor. It is very interesting and full of challenge to fabricate CNTs-based electrochemical sensor (or CNTs-modified electrodes) for electrochemical researchers since the subtle electronic properties suggest that CNTs have the ability to promote electron transfer.In this thesis, carbon nanotubes were successfully dispersed into ethanol and water by utilizing special technology, which expanded the application areas of CNTs. Based on this, some kinds of CNTs-film-modified electrodes have been fabricated. Then, their applications in electroanalysis have been studied with great details. The main researches were summarized as follows:Section one: Study on the MWNT-Nafion composite film-modified electrodeIn the presence of Nafion, an excellent cation-exchange polymer, multi-wall carbon nanotube (MWNT) was easily and homogeneouslyIVdispersed into ethanol. Consequently, a uniform MWNT-Nafion film was obtained on a glassy carbon electrode (GCE) surface via solvent evaporation, and then characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transfer (FT) IR spectra and electrochemical methods. The electrochemical behaviors of dopamine (DA) were examined. In comparison with the bare GCE and the Nafion-modified GCE, the MWNT-Nafion film-modified GCE shows obvious electrocatalytic activity to DA since it not only enhances the peak current but also lowers the overpotential. Moreover, the MWNT-Nafion film exhibits excellent selectivity towards DA even in the presence of high concentration of ascorbic acid (AA) and uric acid (UA).Section two: Studies on the MWNT-dihexadecyl hydrogen phosphate (DHP) film-modified electrodeSurfactant contains hydrophobic group and hydrophilic group, and has been extensively used in electrochemistry. In the presence of dihexadecyl hydrogen phosphate (DHP), which contains two long C-H chains, MWNT was successfully dispersed into water. The resulting MWNT-DHP dispersion is very stable and homogeneous. Through evaporating solvent, a uniform and stable MWNT-DHP film was obtained on the electrode surface.(1) The MWNT-DHP thin film on the electrode surface was characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and some electrochemical techniques such as electrochemical impedance spectra (EIS) and cyclic voltammetry (CV).(2) Utilizing the subtle properties of MWNT (hollow structure, closed topology, strong adsorptive ability and huge specific surface area) and the induced adsorption behavior of I", a sensitive electrochemical technique for the simultaneous determination of Cd2+ and Pb2+ has been developed. This sensing and determining system possesses following advantages: free of mercury, low detection limit, fast response, low cost and excellent reproducibility. Moreover, this proposed method was successfully used to detect Cd2+ and Pb2+ in更多还原