纳米金属胶体的合成及纳米组合电极的制备

【作者】 夏纲；

【导师】 郭荣； 胡效亚；

【作者基本信息】 扬州大学 ， 物理化学， 2002， 硕士

【摘要】 一．银胶修饰金电极的电化学性质 将纳米级的银胶粒子以单层的形式直接吸附于的金电极表面，从而制得银胶修饰金电极。通过控制金电极在银胶溶液中的浸泡时间来确定被修饰银胶的量，发现当浸泡时间在5小时以下时，银胶在金电极表面的覆盖率小于1，而在5-11小时之间时则基本上等于1。测定了制备出的银胶修饰金电极的电化学性质，包括温度对银胶在金电极表面吸附的影响，以及扫描速度与峰电流的二分之一次方两者之间呈线性关系，说明氯离子与银胶粒子在金电极表面上的反应是受物质扩散控制的。在不同的卤素离子溶液中的电化学扫描得到的结果与理论预测是一致的。银胶修饰金电极与普通银电极相比电子的传递速度更快，可逆性更好。 二．银和金的纳米组合电极的制备 直链硫醇很容易在金电极表面形成稳定的自组装单层膜(SAMs)，并且膜本身的稳定性也较好，同时也可以在银胶粒子表面吸附，但作用力较弱。利用这种差异，将制备的单层银胶修饰金电极浸泡在硫醇／乙醇溶液中，可以在金表面和银胶粒子的表面均形成单层硫醇膜。在电极上施加一变频交流电，控制平衡电压为0.0V，频率从100000Hz到1Hz，振幅为0.V，可以选择性的将银胶表面的硫醇分子脱附但是不影响在金电极表面的单层硫醇。通过这种方法可以制备纳米级的银阵列组合电极和金组合电极。扬州大学硕士学位论文三.少量金存在下的铜纳米颗粒的合成 用SDS做保护剂合成纳米铜胶后发现粒子的颗粒易聚集，且颗粒不够均匀。在该方法中加入相当于铜含量的百分之一的四氯合金离子，在还原的过程中，先被还原的金粒子可以充当成核中心，后被还原的铜则继续在金表面生长，改进后的方法明显的改善了粒子的分散性，粒子的尺寸控制在snm左右。文章对铜纳米粒子的合成机理做了简述。紫外可见光谱的研究并没有发现有铜的氧化物的生成。过量的还原剂腆可以使得铜的稳定性更好。四.聚合物做保护剂的铜纳米粒子的合成 铜纳米粒子的合成需要一定的物质做为保护剂。采用大分子量的聚合物一梭甲基纤维素纳做保护剂，将该物质加入到硫酸铜溶液中，在搅拌的情况下均匀加入温和的还原剂脐，在氮气条件下合成的粒子的稳定性要比空气下合成的要好的多。这种方法便宜简单，并可以消除表面活性剂法对后续电化学测定造成的干扰。并对合成的铜胶粒子的紫外光谱性质做了测定。更多还原

【Abstract】 1. Electrochemical properties of silver colloid modified gold electrodeNanoparticles of silver colloid were absorbed to the smooth surface of gold electrode so that the silver colloid modified gold electrode was prepared. The quantity of adsorbed silver colloid was controlled by immersing time of gold electrode in silver colloid solution. Surface coverage of silver colloid on gold electrode was lower than 1 when immersing time was under 5 hours and approximately was 1 as time was between 5 and 11 hours. The electrochemical properties of prepared silver colloid modified gold electrode were investigated including the influence of temperature on adsorption of silver colloid on gold electrode The linear relation between peak current and the square root of scanning rate shows that reaction of chloride ion and silver colloid on surface of the electrode was controlled by diffusion. In different halogen ion solutions, the results of electrochemical scan was same to that of theoretical forcast. Compared with common silver electrode, silver colloid modified gold electrode has some advantages such as faster charge transfer rate and better reversibility.2. Preparation of nanoelectrode ensembles by assembling silver colloids on gold electrodeThiol can easily form the Self-Assembly Monolayers (SAMs) on the surface of gold electrode with desirable stability. Same phenomenon happened on the surface of silver colloid but the interactive force between thiol and silver surface was weak. In terms of this difference, thiol molecules can be assembled to surfaceof silver colloid modified gold electrode when it was immersed into thiol/alcohol solution. Then a a.c. voltage with 0.3V amplitude and frequency range of 100KHz~1KHz was applied to this gold electrode, which led to desorption of the thiol molecules from surface of silver colloids rather than from surface of gold electrode. So that silver nanoelectrode ensembles (SNEEs) and gold nanoelectrode ensembles (GNEEs) were prepared.3. Synthesis of copper nanoparticles protected by surfactant SDS in the presence of small amount of AuCl4*Copper colloids protected by SDS were easily aggregated and the size of particles was not uniform. To improve these drawbacks, one percent of AuCl4- compared to the Copper ion concentration was added. During the process of particle synthesis, the gold ions were firstly reduced into gold cluster as the nuclei upon which copper particles were developed. This method improved the particle size more uniform and the size of particles was controlled to 5nm. No copper oxide was detected when UV-Vis spectrum was studied. Excessive reducer, hydrazine, made the copper colloid particles more stable.4. Synthesis of nano-copper particles protected by polymer moleculesSynthesis of nano-copper particles needs a protective agent to make it stable. Polymer with high molecule weight as a protective agent was added into copper sulfate solution and mild reducing agent, hydrazine, was added into the solution later under the stirring. Nanoparticles synthesized under nitrogen phase are more stable than those under the air. This method was convenient for preparation and the raw material was cheap. UV-Vis spectrum of synthesized copper particles was also studied.更多还原