【作者】 郭伟华；

【导师】 许林；

【作者基本信息】 东北师范大学 ， 无机化学， 2010， 博士

【摘要】 化学修饰电极是指通过各种方法有目的地将具有优良物理∕化学性质的分子、离子、聚合物固定在电极表面,从而得到的具有某些特定功能的一类电极。化学修饰电极具有较高的灵敏度和优越的选择性,现已被广泛的用于电分析测试中。因而选用不同材料、不同修饰方法构筑的新型化学修饰电极必将为其在传感器、催化等领域的发展和应用奠定理论和实验基础。多金属氧酸盐（简称多酸）是一类具有独特的结构和丰富的物理化学性质的金属氧簇化合物。这类化合物的一个主要特点是可以经历一系列可逆的、多步的多电子转移过程。多酸具有丰富的氧化还原性质,非常适合作为修饰电极的材料和电催化剂。因此,设计和开发基于多酸的修饰电极,扩展多酸基修饰电极在电催化、光电催化方面的应用具有重要意义。本论文以多酸为活性组分,结合碳纳米管和纳米二氧化钛独特的物理化学性质,通过自组装技术和溶胶-凝胶技术构筑了新型多酸基化学修饰电极,并将其应用于化学小分子和生物活性分子的电催化、光电催化性能研究。具体内容如下:1.通过交替沉积自组装技术将钒取代的Dawson型钨磷酸K₈P₂W₁₆V₂O₆₂修饰到ITO电极表面。利用循环伏安法详细研究了该电极的电化学行为和稳定性。该电极同时具有对碘酸根的催化还原和对肼的催化氧化能力。计时电流法研究表明该电极对催化氧化肼的响应速度快,检出限低。该工作首次实现了利用多酸基修饰电极对肼的电催化作用,扩展了多酸基修饰电极在电催化方面的应用。2.利用杂多酸良好的电催化能力和碳纳米管优良的导电性,构建了基于杂多酸/碳纳米管的纳米复合膜修饰电极。文中首先通过动电位沉积法将Keggin型杂多酸H₂SiMo₁₂O₄₀修饰到玻碳电极表面,然后再利用电化学自组装法将碳纳米管修饰到电极上,并用紫外可见光谱和电化学方法对该修饰电极的形成过程进行了监测和表征。采用循环伏安法对复合膜修饰电极的电催化性能进行了研究。结果表明,该修饰电极的制备方法可以实现多酸在CNTs表面的有效固定,得到的修饰电极稳定性高,重现性好,并且具有较高的催化活性。3.首次将杂多钨酸盐（P2W18）和碳纳米管修饰到玻碳电极表面并可以保持良好的电化学和电催化活性。文中以壳聚糖为分散剂,得到了稳定的碳纳米管?壳聚糖复合物,然后通过静电自组装方法制备了P₂W₁₈/碳纳米管?壳聚糖修饰电极。采用循环伏安和交流阻抗谱详细研究了该复合物修饰电极的电化学性质及其对过硫酸根和碘酸根的电催化作用。研究表明,碳纳米管的引入增强了膜的导电性,增大了电极的比表面积,提高了P2W18的表面覆盖度。同时该方法极大的提高了多酸/碳纳米管修饰电极的灵敏度和稳定性。4.采用溶胶?凝胶法结合旋涂技术制备了钨磷酸?锐钛矿纳米复合膜(H₃PW₁₂O₄₀–TiO₂)修饰电极,研究了其在Na₂SO₄溶液中的光电化学性能。测试结果表明H₃PW₁₂O₄₀–TiO₂具有良好的光电化学性能。H₃PW₁₂O₄₀与TiO₂复合后,TiO₂表面的光生电子和空穴的快速复合被有效的抑制,从而提高了TiO2的光电性能。氨基酸是生物大分子蛋白质的基本组成单元,对其进行检测和光解研究具有重要意义。文中以门冬氨酸（Asp）为目标分子,研究了H₃PW₁₂O₍40_–TiO₂的光电氧化能力。结果表明,H₃PW₁₂O₄₀–TiO₂对Asp的光氧化动力学服从Langmuir–Hinshelwood动力学方程。更多还原

【Abstract】 The aim of chemically modified electrodes is to carry out the molecular design on the electrode surface. In other words, some molecule, ion and polymer with excellent properties are immobilized on electrode surface and the electrode with specially chemical and physical properties is obtained. And it has been intensively used in electroanalysis due to their high sensitivity and excellent selectivity. Therefore, a new type of chemically modified electrode built by different materials and different strategies should provide a new ideas for its development and application in sensors, catalysis and other areas.Polyoxometalates （POMs）, a well-known class of nanoclusters with much diversity in size, composition, and function, have attracted increasing attention worldwide. One of the most attractive features of POMs is that the metal-oxygen framework can undergo reversible and stepwise, multielectron-transfer reactions. Their very rich redox chemistry makes them suitable for electrode modification, electrocatalysis and electroanalysis. Thus, it has great significance that the design and development of modified electrode based on POMs, extend the application of POMs modified electrode in electrocatalysis and photoelectrocatalysis. In this paper, we focus on the preparation of chemically modified electrodes containing POMs, carbon nanotubes （CNTs） and nanotitanium dioxide by self-assembly and sol-gel technology. The electrocatalytic and photoelectrocatalytic activities for the chemically modified electrodes were investigated to detect small chemistry molecule and biological activity molecular.1. A new electrocatalytic multilayer films electrode, which shows bifunctional electrocatalysis on iodate and hydrazine, was obtained by the layer-by-layer self-assembly of vanadium-substituted phosphotungstate 1,2-K8P2W16V2O62?18H2O （P2W16V2） on ITO electrode. Electrocatlytic activity of P2W16V2 modified electrode towards hydrazine and IO3- was performed using cyclic voltammetry and Amperometry. The proposed modified electrode has high stability, fast response and low detection limit, which extends the application of POMs-based modified electrode in electrocatalysis.2. A novel composite film modified glassy carbon electrode （GCE） based on the heteropolyacid/CNTs was fabricated due to the good electrocatalytic ability of heteropoly acids and excellent electrochemical properties of CNTs. Keggin-type POM （H4SiMo12O40） was potentiodynamic deposited on GCE and then was used as matrix to form multilayer films by electrochemical growth method with the CNTs. Thus-prepared multilayer films and the electrochemical behavior of the composite film modified electrode were characterized by UV–vis spectroscopy and cyclic voltammetry in detail. The preparation process of the modified electrode is simple and convenient. The resulting multilayer films have high stability and good electrocatalytic activity, which opened up a new way for development POMs modified electrode in the actual application.3. We developed a facile strategy for the first time to fabricate heteropolytungstate （P2W18） and CNTs modified GCE. In this work, chitosan was used as a dispersant to form a stable CNTs?chitosan composite, and then prepared P2W18/CNTs?chitosan modified electrode by electrostatic interactions. The electrochemical and electrocatalytic activities for the P2W18/CNTs?chitosan electrode were investigated in detail. The results suggest that the presence of CNTs in the composite film not only enhances the conductivity of the film but also increases the surface area of the electrode and the surface coverage of P2W18. The developed composite electrode greatly enhances the sensitivity and stability of POMs/CNTs modified electrode.4. Phosphotungstic acid?anatase nanocomposite film (H₃PW₁₂O₄₀-TiO₂) was prepared using sol?gel technology, and their photoelectrochemical properties were examined in the Na2SO4 solution. The results demonstrated that H3PW12O40-TiO₂ films possess high photoelectrochemical performance. POMs as electron scavergers can retard effectively the fast electron-hole recombination on the suface of TiO₂, and consequently enhance the photoelectremical response. Amino acids are the basic components units of protein, so that fundamental photodecomposition study of amino acids is of importance.The photoelectrocatalytic property of H3PW12O40-TiO₂ electrode was evaluated by oxidation aspartate （Asp）. The results show that Asp photooxidation kinetics obeys Langmuir-Hinshelwood kinetic equation.更多还原