【作者】 高国玉；

【导师】 力虎林；

【作者基本信息】 兰州大学 ， 分析化学， 2009， 博士

【摘要】 由于碳纳米管具有很高的比表面和电化学稳定性,因此,采用碳纳米管（CNTs）取代导电碳黑合成质子交换膜燃料电池（PEMFC）用电催化剂是近年来一个新的研究方向之一。本论文在对碳纳米管改性及修饰的基础上,深入研究Pt、Pd、Ag与多壁碳纳米管复合材料的设计制备以及电化学催化性能,液/液界面（liquid/liquid interface）被认为是最简单的模拟生物膜模型。这种非互溶界面在过去的几十年中得到了许多人广泛而深入的关注。相当一部分的研究和显著的发展体现在这种模拟生物膜上电荷转移的探索。而完善合理的界面过程动力学理论,对于认识、理解、掌握许多重要的生理过程,揭示生物体内物质和能量的代谢,探究活体内自由基的产生、消除及其致病机理具有重要意义。主要研究内容如下:1.将多壁碳纳米管与（3-氨基丙基）-3-乙氧基硅烷（3-APTES）在去离子水中超声混合,丰富的乙氧基与碳纳米管之间的疏水作用使得碳纳米管表面吸附上一层单分子膜。然后在酸性条件下乙氧键交叉聚合,PtCl₆^2-,PdCl₆^2-或者RuCl₃离子通过静电相互作用吸附在被包埋的碳纳米管表面上,再通过化学还原的方法将其还原为Pt,Pd,Ag和Pt-Ru合金。通过透射电子显微镜和X-射线衍射仪等手段对Pt/MWNTs,Pd/MWNTs和Pt-Ru/MWNTs进行了表征。电化学实验结果表明,Pt/MWNTs对甲醇,乙醇以及Pd/MWNTs,Ag/MWNTs对肼有很好的电催化作用。Pt-Ru合金与Pt相比,对甲醇具有更好的电催化氧化作用。2.在水溶液中,通过电化学方法在多壁碳纳米管表面上修饰一层4-胺基苯甲酸单分子膜,然后将多壁碳纳米管浸入含有Ag（NH₃）₂⁺的溶液中,Ag（NH₃）₂⁺便通过静电作用吸附在4-胺基苯甲酸单分子膜修饰的多壁碳纳米管表面上,然后再通过电化学电位阶跃法将Ag（NH₃）₂⁺还原为Ag纳米粒子。在中性环境中研究了Ag/MWNTs复合材料对水合肼的电催化作用。3、碳纳米管在有过氧化苯甲酰参加的条件下可以捕获芳基自由基形成苯代的碳纳米管,然后在室温下与氯磺酸在四氯化碳中反应生成磺酰化取代的苯代碳纳米管,再通过还原形成巯基苯代碳纳米管。这种有机合成的方法在碳纳米管表面生成了高密度的巯基苯基基团。最后将氯铂酸或氯化钯用乙二醇还原得到负载贵金属的碳纳米管复合材料。TEM和XRD测试表明,Pt纳米粒子的尺寸约为8nm。电化学实验结果表明Pt/MWNTs对乙醇有很好的电催化氧化作用。4.以二茂铁（Fc）,二甲基取代二茂铁（DiMFc）,十甲基取代二茂铁（DMFc）,和合成的1,4-二二茂铁基取代丁二炔（DiFcDiE）为研究对象。我们在石墨碳电极表面覆盖一层硝基苯的有机相,通过改变水溶液中支持电解质的浓度,从而改变有机相中的电解质浓度。研究有机相和水相界面的电化学行为,定量求算出不同二茂铁衍生物与高氯酸根离子的离子对效应。以三二茂铁基取代甲醇为研究对象,将其溶解在硝基苯有机相中,采用薄层电化学法研究其在液液界面上的电子传输系数和界面驱动力之间的关系。更多还原

【Abstract】 Carbon nanotubes （CNTs） had been paid much attention as catalyst support due to the high electrochemical stability and large specific surface area. Fabrication of electro-catalysts for proton exchange membrane fuel cell with carbon nanotubes instead of carbon black as support had been investigated by many researchers and shown promising performances. In this thesis, based on the research of chemical modification and functionalization of carbon nanotubes （CNTs）, synthetic methods of Pt/MWNTs, Pd/MWNTs , Pt-Ru/MWNTs, Ag/MWNTs catalyst and impact factors were studied and their electrocatalytic performances were discussed in detail.A liquid/liquid interface has been suggested as a simple model for biological membranes. Electrochemical investigation at the interface between two immiscible eleetrolyte solutions （ITIES） has received intensive study in the last decades. Considerable interest has been emerging and remarkable developments can be seen in the field of charge transfer at liquid-liquid interface. The liquid-liquid interface is the simplest and most promising model for understanding charge transfer processes in biological systems. Electron transfer at the liquid-liquid interface is fundamentally important for understanding the energy conversion and further investigation in simulated biomembrane.The main results are as follows:1. Embedding the nanotubes within siloxane by hydrophobic interaction; then the siloxane micelles were cross-linked with Si-O-Si framework by addition of hydrochloric acid. Such a structure probably originates from the formation of the micelle in which ammonium groups extrude outside. Therefore, the formation of an ion complex is required because the ion complex has strong hydrophilic property. Finally, a PtCl₆^2- monolayer was adsorbed onto the modified MWNT surface by electrostatic interaction and noble metal nanoparticles or the platinum and ruthium alloy were obtained by reduction. The structure of the resulting Pt/MWNTs, Pd/MWNTs and Pt-Ru/MWNTs were characterized by transmission electron micrograph （TEM） and X-ray diffraction （XRD）. The electrocatalytic properties of the Pt/MWNTs electrode for methanol, ethanol and the Pd/MWNTs electrode for hydrazine have been investigated by cyclic voltammetry. The results of Pt-Ru/MWNTs also show better electro-catalytic activity to methanol than single Pt nanoparticles. 2. In aqueous solution, 4-aminobenzoic acid was covalently grafted on multi-walled carbon nanotubes （MWNTs） by amine cation radical formation in the electrooxidation process of the amino-containing compound. Then, silver （Ag） nanoparticles were electrocrystallized on 4-aminobenzoic acid monolayer-grafted MWNTs by a potential-step method. The structure and nature of the resulting Ag/MWNT composites were characterized by transmission electron microscopy and X-ray diffraction. The electrocatalytic properties of the Ag/MWNT electrode for hydrazine oxidation have been investigated by cyclic voltammetry, high electrocatalytic activity of the Ag/MWNT electrode can be observed. This may be attributed to the small particle size of the silver particles. The results imply that the Ag/MWNT composites have a good application potential in fuel cells.3. Free radicals generated by decomposition of benzoyl peroxide were used to obtain Phenylated multi-wall carbon nanotubes. Phenylated carbon nanotubes were sulfonylation with Chlorosulfonic acid at room temperature. The above-mentioned sulfonylation MWNTs were reduced to form Surface thiolation. On the basis of the functionalized MWNTs, Pt and Pd nanoparticles are well anchored to the nanotube surfaces by reduction. Transmission electron microscopy （TEM） and X-ray diffraction (XRD results show well dispersed nanoparticles on the MWNTs surface whose particle size is about 8 nm. The electrocatalytic properties of the Pt/MWNT electrode for oxidation of ethanol have been investigated by cyclic voltammetry （CV）.4. Ferrocene, dimethylferrocene, decamethylferrocene, and 1, 4-diferrocinyl-1, 3-butadiyne were estimated systematically by conventional cyclic voltammetry （CV） measurements and thin-layer CV. In the thin layer method, the formal potentials of ferrocene and its derivatives shift negatively with the increase of concentration of supporting electrolyte in thin layer. This shift was caused by ion-pair effect between ferrocene and perchlorate ion. Effective formation constants for forming ion pairs are calculated and compared in thin-layer .The finding from this study accentuates the advantages of the thin film method over conventional methods, and permits a quantitative determination of the ion-pair effect using the thin-layer method. The redox behavior of triferrocenyl-methanol, a hydrophobic molecule with three structurally equivalent redox centers, was explored by thin-layer cyclic voltammetry （CV）. The results demonstrate the feasibility of using molecules containing multiple redox centers to study the correlation between the thermodynamic driving force and electron transfer kinetics at liquid/liquid interfaces.更多还原