Preparation And Study On Optical Property Of Gold-silver Alloy Nanoparticles And Metal Nanoparticles Thin Film

In this paper, the preparation of Au-Ag alloy nanoparticles, the synthesis of gold nanoparticles on solid substrate and the fabricate of Au-Ag nanocomposite film were investigated. The main contents of this paper were given as following:1. Au-Ag alloy nanoparticles with tunable composition and size were prepared by using sodium borohydride and sodium citrate as the reducing agent. TEM images showed the alloy nanoparitcles are close to sphere in shape, homogeneous in size distribution and without core-shell structure. The alloy compositions estimated from EDX analysis closely match the starting molar compositions. As the UV-Vis spectra of their solutions show only one plasmon absorption between the absorption peaks of Au and Ag nanoparticles, and the maximum of the plasmon band red-shifts linearly with increasing Au content. We discussed the effect of NaBH4 during the reaction by comparative test, the size of alloy nanopartices can be controlled by changing the content of NaBH4.2. In-situ formation of gold nanoparticles on (3-aminopropyl)-trimethoxysilane (APTMS) modified solid substrate was investigated. The formation of gold nanoparticles are based on the ability of the amino groups of the monolayer to bind AuCl4- ions, followed by the reduction of AuCl4- to Au0 with NaBH4. The particles size can be controlled by the concentration of HAuCl4 during the deposition-reduction process. By repeating the ion binding and reducing cycle, large amount of gold nanoparticles can be generated on the monolayer. UV-Vis spectra and scanning electron microscope (SEM) confirm that the well-dispersed gold nanoparticles are formed on the substrate. From Atomic Force Microscope (AFM) images, we find the particles with characteristic of 3-35nm are generated on the monolayer. 3. The Au nanoparticles coated quartz was immersed into silver enhancer to fabricate Ag nanoparticles thin film. The influence of development time on preparation of Ag nanoparticles thin film was studied. The Au nanoparticles thin film were prepared by a replacement reaction between Ag nanoparticles thin film and HAuCl4, and the Au-Ag nanocomposite film were fabricate by repeating the process of development-replacement. UV-Vis spectra shows the change of optical property of Au and Ag nanoparticles thin film.