【作者】 胡陈果；

【导师】 王万录；

【作者基本信息】 重庆大学 ， 材料学， 2003， 博士

【摘要】 碳纳米管吸引了世界众多的科学家。碳纳米管小的尺寸、强度及其结构显著的物理性质，使得它们有希望成为独特的材料被应用于众多的领域。根据碳纳米管原子的结构，可视为金属和半导体。由于碳纳米管优异的电子特性，当把它用作电极时，有可能增强电子转移反应。但是碳纳米管巨大的分子量，直接导致了碳纳米管的不可溶解性，使得它不容易进行化学反应。然而，当碳纳米管的结构发生特定变化时并产生一些具有反应活性的官能团之后（如羟基和羧基），化学反应就可能进行。对碳纳米管的电化学研究起步较晚，初步的研究发现碳纳米管对某些生物分子的电化学反应有较好的催化作用。值得注意的是在这些研究中，碳纳米管仅仅当作传统电极的修饰材料，比如，将碳纳米管涂在铂、金和玻碳电极上，或者将碳纳米管嵌入石墨电极表层中。如果将碳纳米管视为一种可能的电极材料（不只是修饰材料），有必要系统地研究基于单纯碳纳米管电极的电化学性质。本论文首先讨论了对碳纳米管的不同酸处理方法，并用透射电镜图和傅里叶红外谱表征了处理前后碳纳米管，结果发现经过酸处理后的碳纳米管的端头被打开，并接上了羧基，成为羧基修饰的碳纳米管。通过热电阻和循环伏安法实验，测定了碳纳米管膜电极的导电性和电化学性质。结果表明，决定碳纳米管电化学性质的两个重要因素：一是碳纳米管的活性官能团；另一个是碳纳米管膜的激活能。官能团使得碳纳米管电极具有低的背景电流和平宽的电位窗口；激活能的高低则决定了在电化学反应时电子转移速度的快慢。从对不同方法处理的碳纳米管电极的测试实验中发现，硝酸10分钟处理的碳纳米管电极具备最好的与羧基相关的红外谱和最低的激活能，因此表现出最佳的电化学特性，即小的背景电流，平宽的电位窗口，对于Fe3+ / Fe2+、Fe(CN)63- / Fe(CN)64- 和Hydroquinone / quinone的氧化还原反应有很好的准可逆循环伏响应和快的电子转移速度常数。硝酸10分钟处理的碳纳米管电极可以成为一种新型的电极材料。将经羧基修饰碳纳米管电极应用于对生物分子的电分析。结果表明，与玻碳电极相比，碳纳米管电极对多巴胺、肾上腺素、磺胺嘧啶和抗坏血酸均有较强的催化作用，其中，催化作用使得多巴胺、肾上腺素、磺胺嘧啶的氧化峰电流有很大的增强；而使得抗坏血酸氧化电位负移。原因可能是碳纳米管的微孔管道结构和端头的活性羧基所致。重要的是这种催化作用使得碳纳米管电极在大量抗坏血酸与微量多巴胺或肾上腺素共存下的电化学检测表现出很好的选择性和很高的灵敏度，检测极限达10–7 mol L-1。并实现了在模拟生理pH值溶液中对微量多巴胺或肾上腺素的检测。对微量磺胺嘧啶的检测也给出令人满意的结果。实验发现在低浓度的水溶液中，用碳纳米管电极可以“完全燃烧”有毒有机<WP=6>物苯酚为二氧化碳，并能有效清除有毒无机物联氨和叠氮化钠。它表明碳纳米管电极可以用于电化学处理废水中的有毒成分。控制电化学反应按照电化学燃烧的路径进行需要两个条件，一是较低的被氧化物浓度，二是电极中有大量的羟基存在。由于构成电极的材料是纳米级的，经羧基修饰的碳纳米管电极有大量的羟基存在于电极中，它提供了电化学燃烧的必要条件；碳纳米管的多孔管道结构，使分子或离子能够很容易地通过管道到达羟基所在的场所，此种的纳米结构极大地增强了对有毒化合物的燃烧或清除能力。因此，在氧化过程中几乎没有电极积垢产生，并能保持长时间的电极活性。 为了研究碳纳米管超微电极在生物电分析中的应用，需要一种重要的超微电极的电连接材料---电功能化微米线。因此，本文同时对双向电泳法自组装电功能化微米线的生长机理进行了研究。根据交流电动力学，对微米线生长过程中的电势、场强和电泳力空间分布的解析表达式进行了理论推导，并给出了空间分布图，结果与实验相符合。更多还原

【Abstract】 Carbon nanotubes have attracted the attention of many scientists worldwide. The small dimensions, strength and the remarkable physical properties of the structures of carbon nanotubes make them a very unique material with a whole range of promising applications. Depending on their atomic structure, carbon nanotubes behave electrically as metal or as a semiconductor. Their subtle electronic properties suggest that carbon nanotubes have the ability to promote electron-transfer reactions when used as an electrode in chemical reactions. But as a nanotube is such an unusual macromolecule, it leads to indissolubility and chemical reaction cannot occur. However, chemical reactions might happen on nanotubes when some changes in the structure of nanotubes take place and some active functional groups appear on it, such as hydroxyl and carboxyl. Electroanalytical applications have been found for determining some biomolecules recently, but the carbon nanotubes are only regarded as a kind of modified material to some traditional electrodes, such as, casting carbon nanotubes on Pt, Au and glassy carbon electrode or intercalating carbon nanotubes on graphite electrode. If carbon nanotubes were considered as a potential electrode material (not only modifying material), systematical investigations of the properties on the basis of carbon nanotube electrodes are needed.The chemical modification of carbon nanotubes was carried out using different chemical treatment methods. These modified carbon nanotubes were characterized by TEM image and FTIR spectra. The properties of the conductance and electrochemistry of the carbon nanotube film electrodes are measured by thermal resistivity and cyclic voltammetry experiments. The results showed that two important factors controlled their electrochemical properties: one is the active functional group; another is activation energy of the carbon nanotube film. Among these measurements, the two factors were matched best by 10 minute nitric acid treated carbon nanotube electrode; and this electrode showed the optimal electrochemical behaviors: small background current, flat wide potential windows, well-defined quasi-reversible cyclic voltammetric responses for the familiar redox couples of Fe3+ / Fe2+, Fe(CN)63- / Fe(CN)64- and Hydroquinone / quinone, and rapid electronic transfer constants. Such properties suggest that the carbon nanotube electrode is a novel and promising electrode material.The carboxyl-modified carbon nanotube electrode was applied in bioelectroanalysis. <WP=8>The results showed that the electrode had strong electrocatalysis to dopamine, epinephrine, sulfadiazine and ascorbic acid in comparison with the glass carbon electrode, where the catalysis greatly raised the oxidation currents of dopamine, epinephrine, sulfadiazine; and negatively shifted oxidation potential of ascorbic acid. These behaviors are due to the porous and tubular structure of carbon nanotubes and the active groups on the end of carbon nanotubes. Trace dopamine or epinephrine in the presence of a large excess of ascorbic acid has been determined selectively with high sensitivity at the carbon nanotube electrode, and the limited determination reached 10–7 mol L-1; and satisfactory results of the detection were obtained for the low level sulfadiazine at the carbon nanotube electrode.The complete electrochemical combustion toxic organic compound of phenol into CO2 or elimination of toxic abiotic compounds of azide and hydrazine was found at low level of concentration on the carboxyl modified carbon nanotube electrode, which might be used in electrochemical treatment of toxic components in wastewater. Due to the carboxyl modification of the carbon nanotubes, a large quantity of hydroxyl radicals existed in the electrode, which provided the condition of the electrochemical combustion; and because of the porous tubule of the structure of the carbon nanotube, the molecule or ion in solution could easily pass the tubes and reach the sites of the hydroxyls. The conglomeration of such nanoscale struct更多还原