【作者】 叶晓燕；

【导师】 何品刚； 方禹之；

【作者基本信息】 华东师范大学 ， 分析化学， 2007， 硕士

【摘要】 碳纳米管是一种具有特殊结构的新型一维量子材料,它的发现给材料学界甚至整个科学界带来一场革命。目前,碳纳米管的制备已经趋于成熟。三种主要的制备方法是:电弧放电法、激光蒸发法、化学气相沉积法。纳米碳管的特性是强度高、韧性强、重量轻、性能稳定、柔软灵活、导热性好、表面积大,此外还有许多吸引人的电子性质,其应用是一个无限发展的领域。碳纳米管可作为最细的导线被用在纳米电子学器件中;可用作扫描隧道显微镜或原子力显微镜的探针。此外,碳纳米管的强度比钢高100多倍,是目前可制备出的具有最高比强度的材料;同时碳纳米管还具有极高的韧性,被认为是未来的“超级纤维”,是复合材料中极好的加强材料。碳纳米管不仅可直接作为某些反应的催化剂,还可利用其中空结构制造其它纳米级的高效催化剂。碳纳米管用于修饰电极,可以降低化学物质氧化还原反应的过电位,改善生物分子氧化还原可逆性;其大比表面积有利于酶的固定化,还能促进酶活性中心与电极表面的电子传递;功能化的碳纳米管还能与各种生物分子键合将其固定于电极表面。碳纳米管的这些特性对于提高生物检测的灵敏度和稳定性具有重大意义,为生物传感器领域开辟了广阔的前景。碳纳米管电极的孔结构主要由相互缠绕的管间表面空隙形成,碳纳米管的管间空隙是相互连通的,其孔径都在2-50nm之间,适合电解质的迁移,因此也就决定了其独特的孔结构,在其在作为双电层电容器的电极时,具有很高的比表面积利用率。官能化的碳纳米管不仅能形成双电层电容,而且还是能充分利用准电容储能原理,是超级电容器电极的理想材料。本论文将碳纳米管应用于生物传感器的构建和超级电容器的初步研究,在碳纳米管的应用方面作了新的尝试。本论文分为四章:第一章:绪论介绍了碳纳米管的发现,主要制备方法、结构及分类,并阐释了碳纳米管杰出的物理化学特性。在阐述生物传感器(包括DNA生物传感器和葡萄糖生物传感器)和超级电容器的原理基础上,综述了碳纳米管应用于上述领域的概况及最新发展。第二章:基于电化学聚合聚吡咯/碳纳米管修饰电极构建的电化学交流阻抗DNA杂交传感器以电化学聚合方法构建聚吡咯/碳纳米管复合物修饰玻碳电极,即吡咯单体中加入羧基化多壁碳纳米管,吡咯电化学聚合过程中,碳纳米管被修饰到电极表面。氨基化探针DNA在EDAC条件下共价结合到聚吡咯/碳纳米管修饰电极表面。杂交反应引起电极表面修饰层电子传递阻力减小,降低了电化学体系的阻抗值,以阻抗减小值作为杂交信号。由于聚吡咯/碳纳米管的有效修饰,电极性能得到提高,具有良好的电子传递能力和大的比表面积;杂交传感器具有较好的灵敏度和选择性,对互补链的检测限为5.O×10-12m01/L。本实验介绍的聚吡咯/碳纳米管修饰电极的构建方法在电化学DNA生物传感器中是首次被应用。第三章基于聚吡咯/铂纳米粒子修饰电极的新型电化学葡萄糖传感器聚吡咯固定葡萄糖氧化酶(GOD)的新方法构建了新型葡萄糖传感器。氯铂酸引发吡咯的聚合,同时还原为颗粒均匀的铂纳米颗粒,作为双氧水(H202)氧化的催化剂。葡萄糖氧化酶修饰电极上固定的酶的活性用电化学安培检测葡萄糖表征。测试结果表明此方法明显优于吡咯电聚合固定葡萄糖氧化酶修饰电极。运用聚吡咯的设计方案可以广泛采用这种铂纳米颗粒沉积方法。第四章直立碳纳米管超级电容器的初步研究采用独立双温控加热系统,在低压条件下,以酞菁铁为原料,在石英玻璃基底上气相沉积制备了大面积准直性好、管径均匀的碳纳米管。采用电解质溶液浸润、酸处理、循环伏安扫描三种方法纯化、活化该直立碳纳米管。再以活化后的直立碳纳米管阵列作为原型超电容器的电极,对其进行了循环伏安、交流阻抗等电化学测试。其循环伏安图(CV)呈近矩形,电化学交流阻抗谱图的最大相位角超过80。,循环伏安法和交流阻抗法计算得出的比电容为16-32F/g。并对疏密度不同的两种碳纳米管阵列作为超级电容器电极材料进行比较研究,证明生长致密的直立碳纳米管是超电容器的理想材料。更多还原

【Abstract】 Carbon nanotubes （CNTs） are a new kind of one-dimension quanta material who has unique structures. The discovery of CNTs revolutionizes the area of structural materials or even the whole science. At present three mature methods to synthesize CNTs: arc discharge, laser blaze and chemical vapor deposition have been widely used.Many of CNTs’ properties have been theoretically calculated and experimentally verified: high mechanical strength, high flexibility, low mass density, chemical inertness, large specific surface area, etc. These amazing properties make this material a promising candidate for various applications, such as the most tenuous wire in nanoelectronic devices, field-effect transistors, tips for atomic force microscope, etc. CNTs are considered as "super fiber" used in reinforced materials due to there high flexibility.The application of CNTs most widely employed so far has been the construction of various detection devices, especially biosensors with immobilized biomolecules. As electrodes or modifiers of conventional working electrodes, CNTs have many advantages in electrochemical measurements, such as the large active surface at electrodes of small dimensions, the enhanced electron transfer or the oftenindicated electrocatalytic properties which highly enhanced the sensibility and stability of biosensors.Lots of studies about the applications of CNTs in supercapacitor were carried out for the CNTs’ novel hollow-tube structure, nanometer dimensions, high spscific surface area, conductivity, low resistivity, chemical stability, etc. CNTs have higher valid specific surface area for their more aggregated pores within from 2nm to 50 nm. The electrochemical capacitance of CNTs can be further increased by activating CNTs.The new applications of CNTs in the construction of biosensor and supercapacitor were presented in this paper: Chapter 1 the reviewThe discovery, the synthesis methods, the structure, and the category, especially the marvelous properties of CNTs were presented. On the bases of the principles of biosensors （including DNA biosensors and glucose biosensors） and supercapacitors, the applications of CNTs in above areas were reviewed.Chapter 2 Impedance DNA biosensor using electropolymerized polypyrrole/multiwalled carbon nanotubes modified electrodeAn electrochemical impedance-based DNA biosensor by using a composite material of polypyrrole （PPy） and multiwalled carbon nanotubes （MWNTs） to modify glassy carbon electrode （GCE） was presented. The polymer film was electropolymerized onto GCE by cyclic voltammetry （CV） in the presence of carboxylic groups ended MWNTs （MWNTs-COOH）. Such electrode modification method is new for DNA hybridization sensor. Aminogroup ended single-stranded DNA （NH2-ssDNA） probe was linked onto the PPy/MWNTs-COOH/GCE by using EDAC, a widely used water-soluble carbodiimide for crosslinking amine and carboxylic acid group. The hybridization reaction of this ssDNA/PPy/MWNTs-COOH/GCE resulted in a decreased impedance, which was attributed to the lower electronic transfer resistance of double-stranded DNA than single-stranded DNA. As the result of the PPy/MWNTs modification, the electrode obtained a good electronic transfer property and a large specific surface area. Consequently, the sensitivity and selectivity of this sensor for biosensing DNA hybridization were improved. Complementary DNA sequence as low as 5.0×10^-12 mol/L can be detected without using hybridization marker or intercalator. Additionally, it was found that the electropolymerization scan rate was an important factor for DNA biosensor fabrication. It has been optimized at 20mV/s.Chapter 3 chemical deposition of Pt nanoparticles and its application on glucose biosensor designA new glucose biosensor design based on glucose oxidase （GOD） immobilized by polypyrrole has been described. The polymerization of pyrrole was initiated by a hexachloroplatinate which itself was reduced into Pt nanoparticles and thus served as a catalyst for the H2O2 oxidation. Properties of the produced GOD modified electrode were examined and the activity of the entrapped enzyme was determined by basic application on the amperometric detection of glucose. Much better results were found comparing with the enzyme electrode for which the enzyme was entrapped by the electrochemically polymerized polypyrrole. This kind of technique for Pt nanoparticles deposition can be applied in many cases where polypyrrole is used.Chapter 4 the supercapacitor based on well-alined carbon nanotubes（ACNTs） Large scale vertically aligned carbon nanotubes（ACNTs） with uniform length and diameter were prepared by the pyrolysis of iron（II） phthalocyanine at low pressure. The ACNTs can be activated by electrolyte-activation, acid-activation and electro-activation. The performance of the capacitor based on activated ACNTs was characterized by Cyclic Voltammograms （CVs） which was of rectangular shape, Impedence spectroscopy in which the phase is above 80° and the result specific capacitance was 16 — 32F/g. The tightly-aligned CNTs and loosely-aligned CNTs were compared when they were used as the electrodes of capacitor. In this way, the tightly-aligned CNTs are the most promising material for the supercapacitor.更多还原