Preparation Of Ag & Au Nanoparticles And Their Self-assemble

Noble metal nanoparticles continue to attract widespread attention in many scientific fields. The size and shapes of nanoparticles are important factors that determine their properties and applications. The structure prepared by nano-particles assembly may have many attractive properties.The purpose of this dissertation are to study the preparation of Au nanoparticles, Ag nanoparticles, their 2D organization by electrophoretic deposition. By means of modern characterization methods with TEM, SAED and UV-Vis, the influencing factors, growth mechanism and related properties of these metal nano-materials have been investigated.Size controlled and monodispersed Au nanoparticles have been produced by the reduction of HAuCl4 using TSC as reductant. The results show that the increase of TSC results in the decrease of the particle diameter of Au nanoparticles and the improvement of monodispersity and distribution of Au nanoparticles. The increase of reagents concentrations also results in the decrease of the particle diameter. However, overage of the reagent results in particles congregating.The conductivity of the sol is decreased using semipermeable membrane. Then the electrophoretic deposition is carried out. The increase of the concentration of Au nanoparticles or positive voltage results in the increase of the coated area and the compacting of the 2D organization. However, the stability of the sol is decreased, when the concentration of Au nanopaticles is too high, and supererogatory reaction appears at overage positive voltage. The best time of polarization in the solution is 100s. Over the time, a few percent of the coated area contains multilayers.Multishaped Ag nanoparticles have been produced by the photochemical method with the protection of PVP using TSC as reductants. The kind of light and soft-template are important factors that determine the shape of nanoparticles. The growth tropism of Ag nanoparticles is changed during photoinduced conversion. Nanorods are produced under 253.7 nm light. Nanosprisms are obtained under 365 nm light. And multi-shaped nanoparticle are obtained under the bulb. PVP protected the nanoparticles and changed the growth rate of different aspect of the crytal by coordinating with Ag+.