【作者】 李美超；

【导师】 马淳安；

【作者基本信息】 浙江工业大学 ， 工业催化， 2006， 博士

【摘要】 导电聚合物具有独特的电化学和化学性能，广泛应用于电池、传感器、腐蚀防护和电催化材料等领域。聚苯胺（PAN）和聚吡咯（PPy）等导电聚合物具有价格低廉、易合成等优点，电催化性能是导电聚合物的重要性能之一。本论文主要研究导电聚合物对有机小分子及氨基酸的电催化性能，研究内容包括以下五个方面。采用循环伏安法制备了一种新型的导电聚合物—苯胺和环氧丙烷导电高分子共聚物（PAN-PPO），并对其可能的共聚机理进行了探讨。采用扫描电子显微镜（SEM）和差热分析等方法对聚合物的形貌和热稳定性进行了表征，同时探讨了该共聚物对甲醇和甲酸的电催化氧化作用。结果表明，在相同的条件下，PAN-PPO的电聚合速率和电导率均高于PAN；PAN-PPO具有均匀的纳米纤维网状结构，纤维直径小于70nm；PAN-PPO的热分解温度略低于PAN；PAN-PPO对甲酸和甲醇具有较好的电催化活性。在1-乙基咪唑三氟乙酸（HEImTfa）、1-丁基-3-甲基咪唑硫酸氢盐（BMImHSO₄）和1-丁基-3-甲基咪唑磷酸二氢盐（BMImH₂PO₄）等离子液体中合成了PAN和PAN-PPO，并采用红外光谱和SEM技术对其进行表征，同时研究了它们对有机小分子的电催化活性。结果表明，在HEImTfa离子液体中合成的PAN（PAN-HEImTfa），由均匀规则的纳米结构组成，与在硫酸水溶液中合成的PAN相比，PAN-HEImTfa对甲酸、甲醛和草酸具有较好且稳定的电催化活性；在BMIHSO₄中，采用循环伏安法合成PAN-PPO（PAN-PPO-BMIHSO₄），PAN-PPO-BMIHSO₄由直径小于80nm的纳米纤维组成，对草酸具有较好的电催化性能；在BMIH₂PO₄中，采用循环伏安法合成了PAN-PPO（PAN-PPO-BMIH₂PO₄），其结构致密，由直径约为100nm的纳米纤维组成，对草酸具有一定的电催化活性。同时，研究发现离子液体的粘度对导电聚合物的合成及其电催化活性的影响较大。上述三种离子液体的粘度大小顺序为BMImH₂PO₄＞BMIHSO₄＞HEImTfa，PAN和PAN-PPO在离子液体中的电聚合容易程度顺序为HEImTfa＞BMIHSO₄＞BMImH₂PO₄，而所得到的导电聚合物的纳米结构尺寸大小顺序为PAN-PPO-BMIH₂PO₄＞PAN-PPO-BMIHSO₄＞PAN-HEImTfa，电催化活性顺序为PAN-HEImTfa＞PAN-PPO-BMIHSO₄≈PAN-PPO-BMIH₂PO₄。在导电聚合物上修饰铂微粒，通过铂颗粒和导电聚合物的协同作用，有利于改善其电催化活性，减少铂颗粒的用量。本论文采用循环伏安法在预先合成的PAN-PPO上负载铂颗粒（Pt／PAN-PPO），Pt颗粒大小约为60nm。研究发现Pt／PAN-PPO对赖氨酸和甘氨酸具有较高的电催化活性，铂的沉积周数不宜超过9周。在离子液体HEImTfa中合成PPy（PPy-HEImTfa），研究了不同电聚合方法和基底电极对PPy的电聚合速度、形貌特征和电催化性能的影响。采用循环伏安法制备PPy-HEImTfa，以铂电极为基底电极时得到的PPy-HEImTfa颗粒较不锈钢基底时的小，而且其电聚合速度和电催化活性均大于在不锈钢基底电极上合成的PPy-HEImTfa。当在同一铂电极上制备PPy-HEImTfa，采用恒电流方法制备的聚合物颗粒直径比循环伏安法小得多。由于纳米碳管具有良好的导电性，高稳定性和良好的机械性能，本文采用循环伏安法制备了PPy和纳米碳管复合电极（PPy／CNT），并研究了PPy／CNT复合电极的电催化性能。结果表明：以铂为基底电极时PPy／CNT复合电极对草酸的电催化性能较好；而当以不锈钢为基底时，PPy／CNT复合电极对草酸也表现出一定的电催化活性，但其活性较铂电极上的PPy／CNT差。更多还原

【Abstract】 Conducting polymers, which exhibit a wide range of novel electrochemical and chemical properities, have been employed in a variety of applications, such as batteries, sensors, antistatic coatings, electrocatalysts and so on. Conducing polymers, such as polyaniline （PAN） and polypyrrole （PPy）, are cheap and can be easily prepared. One of the most important properties of the conducting polymers is their ability to catalyze some electrochemical reactions. In this paper, electrocatalytic activity of conducting polymers on electrooxidation of small organic molecules and amino-acids has been studied, including the following five parts.A novel copolymer of polyaniline-poly（propylene oxide） （PAN-PPO） film is prepared by cyclic voltammetry in this paper. The electrochemical copolymerization mechanism of PAN-PPO has been discussed. PAN-PPO is characterized with SEM and thermogravimetric analysis. In addition, the electrocatalytic activity of PAN-PPO for electrooxidation of methanol and formic acid has been investigated. Results show that under the samilar conditions, polymerization rate and conductivities of PAN-PPO are higher than those of PAN. The structure of PAN-PPO is a cross-linked network, composed of many uniform and regular nano-fibers with diameter less than 70 nm. The degradation temperature of PAN-PPO is a little lower than that of PAN. In comparison with PAN, PAN-PPO shows a high electrocatalytic activity for electrooxidation of methanol and formic acid.The paper has demonstrated the preparation and electrocatalytic activity of PAN and PAN-PPO prepared in ionic liquids, such as HEImTfa, BMImHSO₄ and BMImH₂PO₄. PAN and PAN-PPO are characterized with SEM. In comparison to PAN prepared in H2SO4 solution, PAN prepared in HEImTfa （PAN-HEImTfa） is composed of significantly regular nano-particles and shows a high electrocatalytic activity on electrooxidation of formic acid, formaldehyde and oxalic acid. PAN-PPO can be prepared in BMImHSO₄ by cyclic voltammetry （PAN-PPO-BMImHSO₄）. It is composed of nanofibers with diameter less than 80 nm and can electrolyze the electrooxidation of oxalic acid. PAN-PPO can also been synthesized in ionic liquid BMImH₂PO₄ （PAN-PPO-BMImH₂PO₄）. It is dense and composed of the nano-fibers about 100 nm. The electrocatalytic activity of PAN-PPO-BMImH₂PO₄ on oxidation of oxalic acid is also high and stable. Electropolymerization of conducting polymers in ionic liquids is related to the viscosity of ionic liquids. The viscosity order of ionic liquids is BMImH₂PO₄＞BMIHSO₄＞HEImTfa, and the easiness order of electropolymerization in ionic liquid is HEImTfa＞BMIHSO₄＞BMImH₂PO₄. The diameter order of conducting polymers prepared in the ionic liquids is PAN-PPO-BMIH₂PO₄＞PAN-PPO-BMIHSO₄＞PAN-HEImTfa, and the electrocatalytic activity order is PAN-HEImTfa＞PAN-PPO-BMIHSO₄ PAN-PPO-BMIH₂PO₄.Conducting polymers can be used as supports for platinum catalyst panicles deposition. With the synergistic effect of conducting polymers and platinum panicles, the electrocatalytic activity can be greatly improved and use of platinum can be decreased. In this paper, Pt/PAN-PPO is prepared by Pt deposition onto a pre-synthesized PAN-PPO film （Pt/PAN-PPO）. The diameter of Pt panicles on PAN-PPO is about 60 nm. The electrocatalytic activity of Pt/PAN-PPO has been studied on the electrooxidation performance of lysine and glycine in sulfuric acid solution. Pt/PAN-PPO shows high electrocatalytic activity on electro-oxidation of lysine and glycine, and the cycling number of Pt on PAN-PPO should be less than 9.PPy has been prepared in ionic liquid HEImTfa （PPy-HEImTfa）. The influences of polymerization method and support electrode on polymerization rate, morphological structure and electrocatalytic activity of PPy-HEImTfa are investigated. Polymerization rate and the electrocatalytic activity of PPy-HEImTfa by cyclic voitammetry on Pt are higher than those on stainless steel, and the particle diameter of PPy-HEImTfa on Pt is less than that on stainless steel. In addition, on the same Pt support electrode, the panicle diameter of PPy-HEImTfa prepared galvanostatically is much less than that by cyclic voltammetry,Carbon nanotube （CNT） owns excellent conductivity, high stability and good mechanical properties. Electropolymerization of PPy/CNT composite is carded out using cyclic voltammetry. The electrocatalytic activity of PPy/CNT composite has been studied in this paper. Results show: PPy/CNT prepared on Pt exhibited excellent electrocatalytic activity for electro-oxidation of oxalic acid. In addition, electrocatalytic activity of PPy/CNT on Pt is better than that on stainless steel.更多还原