【作者】 刘继伟；

【导师】 缪煜清；

【作者基本信息】 浙江师范大学 ， 物理化学， 2009， 硕士

【摘要】 纳米材料具有比表面积大、催化活性高、亲和力强等特点,在电催化及传感器材料领域有着广阔的应用前景。研究表明,电化学过程与电极材料的表面性质密切相关。由于该材料的尺寸效应和介电限域效应等特性,将纳米材料修饰到电极表面,能增加电流响应,降低检测限,大大提高检测的灵敏度。本论文致力于纳米材料修饰电极的制备及其电催化性能的研究,修饰电极过程简单、方便,实现了将纳米材料、修饰电极和电分析化学三者的有机结合。主要工作如下:1.聚吡咯-铂（PtPPy）复合纳米粒子的制备与表征及其电化学性质采用CTAB作为分散剂,一步合成PtPPy复合纳米粒子。并应用紫外-可见分光光度计（UV-vis）,扫描电子显微镜（SEM）,红外光谱（IR）,热重分析（TA）等方法进行表征。该材料修饰电极的过程简单,可以不借助其它分子而直接吸附到Au电极表面。PPy的存在,阻止了铂纳米粒子的进一步团聚,而且修饰电极更加稳定,对O₂表现出较好的电催化还原活性。此材料有望应用于燃料电池和生物传感器领域。2.聚吡咯-金（AuPPy）复合纳米粒子的制备及其电催化还原氧气纳米金的比表面积大,反应活性高,表面活性中心多,吸附能力强,稳定性好和催化性能高,常常用于自组装电极的设计和制备各种特定功能的化学传感器。本文制备了AuPPy复合纳米材料并研究了其电催化性能。SEM可以看出,AuPPy复合纳米粒子为球形颗粒。AuPPy可以直接吸附到Au电极表面,表现出比裸Au电极更好的电催化活性。这种方法合成的AuPPy用于修饰电极可以不借助其它连接剂直接固定到电极表面,避免纳米粒子离心、洗涤的复杂过程。进一步研究了漆酶固定在AuPPy修饰电极上的直接电化学行为,并采用2,2′-连氮-双（3-乙基苯并噻唑-6-磺酸）（简称ABTS）作为电子介体,研究了漆酶修饰电极对O₂的电催化还原。结果表明该材料修饰电极有良好的稳定性和生物兼容性,可用于金属纳米粒子修饰电极和生物传感器的研制。3.生物多肽为稳定剂制备聚吡咯-金或铂的纳米复合物用于修饰电极及其电催化研究两亲性生物多肽多粘菌素B（PMB）具有很好的亲水性,在水溶液中容易形成稳定的胶束结构,可作为制备纳米材料的分散剂。本文在PMB的存在下,用吡咯单体一步还原HAuCl₄或K₂PtCl₆,得到稳定的、分散均匀的AuPPy、PtPPy胶体溶液。此外,将胶体溶液直接滴加到Au电极表面,溶剂挥发后,残留的复合纳米粒子可以强烈吸附到Au电极表面,所得修饰电极电子转移效率增强,对O₂电催化还原明显优于裸Au电极,该方法可用于制备贵金属纳米粒子修饰电极并应用于电催化和电分析领域。4、血红素直接自组装在碳纳米管修饰电极上的电化学性能制备了血红素/碳纳米管修饰电极,并研究对O₂、H₂O₂及对-SH化合物的电催化行为。结果表明,该修饰电极的循环伏安曲线有一对对称的氧化还原峰,峰位差为61mV,峰电流与扫描速率、式电位与pH均成线性关系。碳纳米管的存在,一方面起到固定血红素的作用,另一方面促进了电子传递,增加电流响应,提高了检测的灵敏度。碳纳米管/血红素修饰电极有望应用于生物传感器和电分析研究。更多还原

【Abstract】 Nanomaterials have been studied extensively due to their large specific area, high surface activity, and strong affinity. Also they indicate the wide application prospect in electrocatalysis and sensor materials. The electrochemical responses of modification of electrodes are related to the electrode materials. Current response can be improved and detection limit extended when the nanomaterial modified electrodes are employed. The main work of this paper is focus on preparation of nanomaterial modified electrodes and study of the electrocatalytical properties. Compared with the traditional modified electrodes, the process of preparation is simple and convenient. Besides, the other emphasis of the work is to apply these nanomaterials modified electrodes to detect and analysize some analysts, such as oxygen, hydrogen peroxide, L-cysteine. The details are listed below:1. Preparation and characterization of Pt-polypyrrole nanocomposites for electrochemical reduction of oxygen.An easy and simple method of one-step reaction was employed to synthesize the platinum-adsorbed polypyrrole nanocomposite （PtPPy） in a cetyltrimethylammonium bromide （CTAB） solution. The prepared nanocomposites were characterized using UV-vis absorption spectroscopy（UV-vis）, scanning electron microscopy（SEM）, Fourier transform infrared spectroscopy（IR）, thermogravimetric analysis（TA）, and cyclic voltammetry（CV）. Polypyrrole within nanocomposites could crosslink to improve its stability on the Au substrates. O₂ reduction was performed at Au electrodes modified PtPPy. The results clearly show that modification of PtPPy nanocomposites results in the enhancement of the electrocatalytic reduction of oxygen. The nanocomposites may provide a novel electrode material for application in fuel cells and oxygen sensors.2. Preparation of Au-polypyrrole composite nanoparticles and study of their electrocatalytical reduction to oxygen with （without） laccasse.Au nanoparticles are often employed to design self-assembling electrodes and prepare functionalized sensors due to their characteristics, such as the large surface-to-volume ratio, high activity and strong absorbtion. In the section, the colloids of Au-polypyrrole （AuPPy） composite nanoparticles were prepared by oxidizing pyrrole monomer with HAuCl₄ in a cetyltrimethylammonium bromide （CTAB） solution. Scanning electron microscopy （SEM） suggests the AuPPy nanoparticles in the form of regular spheres, approximately 200 run in diameter. The resulting colloid of AuPPy composite nanoparticles strongly adheres to the surface of Au electrodes and exhibits better electrocatalytical reduction of oxygen than bare Au electrodes. It means that the complex procedures of centrifuge and wash are avoided. Also, no linker molecules are needed and the immobilization of nanoparticles is achieved easily in a single-step procedure. The direct electron transfer of laccase is observed after it is immobilized on AuPPy modified electrodes by glutaraldehyde. With the help of mediator 2,2’-azino-bis-（3-ethylbenzothiazoline-sulfonic acid）（ABTS）, laccase electrode gives an electrocatalytical reduction wave of oxygen. It is proved that these nanocomposites not only have a stable electric signal, but show the environmental compatibility for biomolecule. These materials are excellent choice for the design of metal nanoparticles modified electrodes or biosensors.3. Direct assembly and electrochemical study of Au-polypyrrole and Pt-polypyrrole composite nanoparticles in the colloids with bioderivative peptide polymyxin B as stabilizer.The amphipathic molecule polymyxin B（PMB） is employed dispersion nanopaticles. The hydrophilic property of PMB is excellent. The stable colloids of Au-polypyrrole or Pt-polypyrrole composite nanoparticles were prepared by oxidizing pyrrole monomer with HAuCl₄ or K₂PtCl₆ respectively in the presence of PMB. On the one hand, the Au-polypyrrole and Pt-polypyrrole composite nanoparticles are dispersed well in colloid solution due to excellent hydrophilic property of PMB. On the other hand, after the colloid solution is spread on Au surface followed by the evaporation of the solvent, the resulting composite nanoparticles strongly adhere to the Au surface due to the existence of polypyrrole. It is a facile and versatile route to immobilize Au-polypyrrole or Pt-polypyrrole nanoparticles. The composite nanoparticles exhibit better electron transfer and electrocatalytical reduction of oxygen than bare Au electrodes. It makes these polypyrrole-based composite nanomaterials an excellent choice to prepare noble metal nanoparticle-modified surface for electrocatalytical or electroanalytical applications.4. Electrochemistry of self-assembled hemin from hexadecyl trimethyl ammonium bromide （CTAB） water solution on single wall carbon nanotube modified glass carbon electrodes.The hemin is adsorbed on the surface of single-wall carbon nanotube modified GC electrodes by self-assembly. The modified electrodes exhibit a well-defined, reversible redox peaks with the reduction potential at -0.30V and potential separation of 61mV at pH 7.0. The peak current is found to increase linearly with the scan rate in the range of 25-200mV and the peak potential to be pH dependent. The modified electrodes exhibit obvious signal enhancement for the electrochemical reduction of O₂ and H₂O₂, and oxidation of cysteine, which is useful to develop their application in electroanalysis and biosensors.更多还原