金纳米粒子的电化学合成及其自组装

【作者】 黄绍鑫；

【导师】 马厚义； 骆静利；

【作者基本信息】 山东大学 ， 物理化学， 2006， 硕士

【摘要】 相对于化学方法，电化学法在制备金属纳米材料方面有许多优点，例如，产物纯度高，能更好地控制纳米粒子的尺寸和形貌等。我们设计了旋转阴极，并使用它通过电化学还原反应来合成尺寸和形状可控的纳米金属材料。旋转电极的优点是可以有效地加速金属纳米粒子从电极表面到体相溶液的转移速度。具有较强络合性能的多官能团聚合物和表面活性剂被用作纳米粒子的稳定剂和形状控制剂。使用旋转阴极可以在纳米粒子稳定剂存在的条件下通过简单的电化学还原方式较大规模地合成形状和尺寸可控的金属纳米材料。 在聚乙烯吡咯烷酮（PVP）作为保护剂的电解液中，尺寸可控的金纳米晶体可以通过电化学还原AuCl₄^-阴离子很方便地合成出来。PVP能促进金纳米粒子的形成过程，并且显著地抑制其电沉积过程，这就决定了金纳米晶体可以通过简单的电还原过程合成得到。这种新颖的方法还有望用于其它尺寸可控的的贵金属纳米粒子的合成。 我们研究了电化学法合成贵金属纳米粒子过程中聚乙烯吡咯烷酮的作用机理，同时研究了金纳米粒子的生长过程和机制，从而可以对这种合成方法进行优化和改进。 以这种方法为基础，通过适当地改变其他反应条件，我们还合成了单分散性很好的金纳米球形粒子、纳米棱柱和纳米多面体。 PVP K90保护的金纳米晶能够自发地组装成二维密堆积阵列和奇特的一维纳米结构。以PVPK17作为保护剂的金纳米晶体可以通过粒子间的聚集形成超薄的单晶纳米膜。在单晶纳米膜的形成过程中PVP起到了多种作用，既控制了金纳米晶的尺寸和形状，又促进了单个金纳米晶通过粒子间的聚集和熔合构建二维纳米结构材料。以聚乙烯吡咯烷酮为基础的自组装技术，为我们提供了一种简单而且有效地把单个金纳米晶组装成不同的一维和二维纳米结构材料的有效途径。更多还原

【Abstract】 Some advantages of electrochemical methods over chemical methods in synthesis of metal nanostructures are the high purity of products and good control of size, shape, and morphology of the nanostructured materials. We are interested in the size-selective and shape-controlled electrochemical synthetic methods. By using a rotating working as the cathode, which greatly accelerates the transfer of metallic nanoparticles from electrode/solution interface to the bulk solution, and the multifunctional ligands, polymers, and surfactants as the stabilizers or shape-controllers, a large number of nanostructured metallic materials can be synthesized through a simple electroreduction of metal ions.Size-controlled gold nanocrystals were conveniently synthesized through direct electroreduction of bulk AuCl₄^- ions in the presence of poly（N-vinylpyrrolidone） （PVP）. PVP greatly enhanced the gold particle formation process and also significantly retarded the gold electrodeposition process, allowing the electrochemical synthesis of gold nanocrystals to be carried out in the form of simple electroreduction. This novel electrochemical method may be extended to synthesis of other noble metal nanoparticles with controllable size on a large scale.We investigated formation mechanism of PVP-protected gold nanocrystals and other functions of PVP in organizing individual noble metal nanoparticles into ordered nanostructures. Based on the electrochemical synthetic methods, well-defined gold nanoprisms, well-dispersed spherical and polyhedral nanoparticles were synthesized .The PVPK90-protected gold nanocrystals spontaneously self-assembled into nearly ordered 2D close-packed arrays and interesting 1D nanostructures. The aggregation of unstable PVPK17-protected gold nanocrystals resulted in the formation of ultrathin single-crystalline films. PVP plays multifunctional roles in controlling the size and shape of gold nanocrystals and in inducing individual gold更多还原