金纳米团簇薄膜的量子化充放电现象研究

发布时间：2018-05-20 08:14

本文选题：MPC薄膜 + 电化学充放电　；参考：《浙江大学》2015年博士论文

【摘要】：纳米科学和技术作为现代研究的重要领域在过去二十多年间发展迅速。纳米材料具有介于宏观固体和原子／分子材料之间的新物理化学性能,体现在强度、电导率、热导率、光学响应、弹性和耐磨性等方面。通过对纳米材料的理性设计,能够发现许多独特的性质和性能。单层保护金纳米团簇作为纳米材料研究的一个重要分支,由于其独特的量子化充放电现象而备受关注。基于上述研究背景,本论文主要开展了单层保护金纳米团簇薄膜的量子化充放电现象研究并探讨了其在化学传感领域的应用。本论文共分三部分。第一部分为第一章,简要介绍了纳米材料种类及特性,总结了单层保护金纳米材料的合成方法,晶体结构解析及演变过程,能级量子化和量子化电化学充放电性质。第二部分包括第二章和第三章,研究了烷基硫醇单层膜保护的金纳米颗粒(以下简称MPCs)薄膜的量子化充放电现象。第二章首先研究了MPCs多层膜在水溶液中还原充放电现象被抑制的原因。采用强疏水性阳离子为对离子,首次观察到了量子化还原充放电峰,并用电化学石英晶体微天平技术进行了跟踪监测。结果表明MPCs多层膜在水溶液中的还原充放电过程是一个离子耦合的电子反应,即MPCs的在电极／膜界面的还原必须伴随着膜／溶液界面的阳离子转移过程。随后,研究了MPCs多层膜在水溶液中还原充放电电子转移的动力学。通过电位阶跃计时电流法测得MPCs膜内扩散式的电子跳跃(自交换)过程一级动力学常数数量级为104 s-1,其大小接近于膜在有机相中的转移常数,而与固态干膜的转移常数相差较大。由此可知溶剂溶胀作用对MPCs多层膜内电子转移动力学过程几乎没有影响,即对离子的扩散为控速步骤。此外,在含氯离子的水溶液中,MPCs多层膜的电化学充放电现象发生明显的不可逆衰减,进而研究了MPCs与氯离子的反应活性。通过循环伏安法、电化学石英晶体微天平和X.射线光电子能谱跟踪并分析了实验过程。结果表明氯离子对MPCs表面有很强的亲和力,能够部分取代了表面的烷基硫醇保护链导致表面结构的变化,从而猝灭MPCs电化学充放电现象。最后,比较了MPCs单层膜和MPCs多层膜的充放电现象的区别。MPCs单层膜在体积相对较小的对离子溶液中能观察到电化学充放电现象,然而在体积相对较大的对离子溶液中则不出现量子化充放电现象。究其原因在于MPCs能否与对离子形成有效离子对。只有足够小的对离子才能渗入MPCs表面的烷基硫醇保护层之内,进行有效的电荷补偿。相反的,体积较大的对离子由于尺寸排阻,无法形成离子对。以上结果有助于我们更好的理解MPCs膜与对离子之间存在的相互作用。第三章在第二章工作的基础上,将MPCs薄膜拓展到非水体系中。离子液体是一种易于控制离子组成(阳离子和阴离子)来获得所需结构和功能的“可设计性溶剂”,十分适于研究离子对MPCs量子化充放电过程的影响。首先,研究了在咪唑类离子液体中MPCs薄膜的量子化充放电现象。与水溶液中观察到的离子整流现象相似,MPCs膜在咪唑类离子液体中呈现与阴离子性质相关氧化充放电行为。相比之下,采用强疏水性的四己基铵阳离子,则可以观察到MPCs的量子化还原充放电现象。此结果证明MPCs膜充放电是一个离子转移耦合的电子转移的过程,即MPCs在电极／溶液界面的氧化还原过程伴随着膜／离子液体界面的离子转移过程。由于离子液体的可设计性,以上结果提供了一条通过调控离子／溶剂性质来控制纳米颗粒薄膜电子性能的有效途径。此外,研究了MPCs薄膜在极性有机溶剂中的氧化还原充放电现象。与极性水溶液和弱／非极性有机溶剂中的现象不同,在疏水性电解质存在下,MPCs薄膜的氧化充电首峰和还原充电首峰间有一个非常明显的电位差。结合之前的研究,可知MPCs薄膜的量子化氧化还原总反应是一个离子传输和电子转移相耦合的过程,受到MPCs膜／溶液界面对离子转移的热力学的影响和MPCs膜内扩散式电子跳跃的动力学控制。第三部分为第四章,通过在ITO电极表面修饰MPCs薄膜的简单方法,建立了检测维生素E (Trolox)的电化学传感器。维生素E是一种重要的食物抗氧化剂,检测其含量有助于了解食物的抗氧化能力大小。ITO电极表面修饰MPCs薄膜有助于提高表面疏水性,不仅减小了维生素E的反应电位,还提高了其反应电流。茶叶样品的测量进一步说明检测方法具有很好的抗干扰性和检测效果。
[Abstract]:Nanoscience and technology have developed rapidly in the past more than 20 years as important fields of modern research. Nanomaterials have new physical and chemical properties between macroscopic solid and atomic / molecular materials, which are reflected in strength, conductivity, thermal conductivity, optical response, elasticity and wear resistance. Many unique properties and properties are found. As an important branch of nanomaterials, single layer protective nanoclusters have attracted much attention due to their unique quantized charge and discharge phenomena. Based on the above research background, this paper mainly studies the quantized charge discharge phenomenon of single layer protective nanocluster thin films and discusses the phenomenon. Its application in chemical sensing field is divided into three parts. The first part is the first chapter. The first chapter is a brief introduction of the types and characteristics of nanomaterials, summarizes the synthesis methods of single layer protective gold nanomaterials, crystal structure analysis and evolution process, energy level quantization and quantized electrification charge and discharge properties. The second part includes second chapters and the first part. In the three chapter, the quantized charge discharge phenomenon of the gold nanoparticles (hereinafter referred to as MPCs) films protected by alkyl mercaptan monolayer is studied. The second chapter first studies the reason for the inhibition of the reduction of the charge discharge in the aqueous solution of the MPCs multilayer. The electrochemical quartz crystal microbalance technique has been tracked and monitored. The results show that the reduction charge and discharge process in the aqueous solution of MPCs multilayer films is an ion coupled electron reaction. That is, the reduction of MPCs at the interface of the electrode / membrane must be accompanied by the cation transfer process at the membrane / solution interface. Then, the MPCs multilayer film is studied in aqueous solution. The kinetics of electron transfer in the redox charge discharge is measured by the potential step chronocurrent method. The magnitude of the first order kinetic constant of the MPCs membrane diffusion (self exchange) process is 104 s-1, which is close to the transfer constant in the organic phase, and the difference is much different from that of the solid dry film. There is almost no effect on the kinetic process of electron transfer in MPCs multilayer, that is, the diffusion of ions is the step of control. In addition, the electrochemical charge and discharge of the MPCs multilayer film is obviously irreversible in the aqueous solution of the chloride ion, and the reaction activity of MPCs with the chloride ion is studied. The experimental process was tracked by crystal microbalance and X. ray photoelectron spectroscopy. The results showed that the chloride ion had a strong affinity to the surface of MPCs, which could partially replace the surface structure change of the alkyl thiol protection chain, and then quenched the MPCs electrochemical charge and discharge phenomenon. The most later, compared the charge of the MPCs monolayer and the MPCs multilayer film. The difference in discharge phenomenon.MPCs monolayer can observe the electrochemical charge and discharge phenomenon in the ionic solution with relatively small volume. However, there is no quantized charge discharge phenomenon in the relatively large volume of ionic solution. The reason is that MPCs can form the effective ion with the ion. Only small enough against ions can be used to permeate the ion solution. The effective charge compensation is carried out within the alkyl thiol protective layer on the surface of the MPCs. On the contrary, the larger volume of ions can not form the ion pair due to the size exclusion. The above results help us to better understand the interaction between the MPCs film and the ions. The third chapter extends the MPCs film to the second chapter. In non water system, ionic liquid is a "design solvent" which is easy to control the structure and function of ion composition (cation and anion). It is very suitable for the study of the effect of ion on MPCs quantized charge discharge process. First, the quantized charge discharge phenomenon of MPCs film in imidazole ionic liquid and water solubility are studied. The ion rectifying phenomenon observed in the liquid is similar, and the MPCs film presents an oxidation charge discharge behavior associated with the anionic property in imidazole ionic liquids. By contrast, the quantized reduction charge discharge of MPCs can be observed by the strong hydrophobicity of four hexyl ammonium cation. This result shows that the charge and discharge of the MPCs membrane is an ion transfer coupling. The process of electron transfer, that is, the redox process of MPCs at the interface of the electrode / solution is accompanied by the ion transfer process of the membrane / ionic liquid interface. Due to the feasibility of the ionic liquid, the above results provide an effective way to control the electronic properties of the thin film by controlling the properties of the ionic / solvent. In addition, the MP has been studied. The redox charge and discharge phenomenon of Cs film in polar organic solvents is different from that in polar water solution and weak / non polar organic solvent. In the presence of hydrophobic electrolyte, there is a very obvious potential difference between the first peak of the oxidation charge and the first peak of the reduction charge in the MPCs film. The quantum of the MPCs thin film is known by the previous study. The total redox reaction is a process of coupled ion transmission and electron transfer phase, which is influenced by the thermodynamics of the ion transfer at the MPCs film / solution interface and the kinetic control of the diffusion electron hopping in the MPCs membrane. The third part is the fourth chapter. A simple method of modifying the MPCs film on the surface of the ITO electrode has been established. Vitamin E (Trolox) electrochemical sensor. Vitamin E is an important food antioxidant. Detection of its content helps to understand the antioxidant capacity of food. The surface modification of MPCs film on the surface of.ITO electrode helps to improve the surface hydrophobicity, not only reduces the reactive potential of vitamin E, but also improves the reaction current. The measurement of the tea samples is also improved. One step shows that the detection method has good anti-interference and detection effect.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O657.1;TB383.2

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