Preparation And Characterization Of Gold, Silver And Copper Nanoparticles

How to prevent aggregations efficiently for the synthesis of metallic nanoparticles has become a key technology owing to large surface area, surface activity, easy to aggregate and weak stability. In this paper, micro-structures of metallic nano-materials have been controlled efficiently by using different surfactants to reduce the aggregation of metallic nanoparticles. In different reaction systems, gold nanoparticles, silver nanoparticles and copper nanoparticles have been synthesized by changing the reaction conditions, and the effects of different reaction conditions and optical properties on the synthesis processes of gold nanoparticles, silver nanoparticles and copper nanoparticles have been investigated systematically.Gold nanoparticles have been synthesized by using PVP (polyvinylpyrrolidone) and KH-550 (3-aminopropyl-triethoxysilyl) as surfactants, chloroauric acid as precursor, water and DMF (N, N-dimethylformamide) as solvents respectively through wet chemical route. The optical properties and morphologies of the synthesized gold nanoparticles have been determined through UV-visible absorption spectrum and transmission electron microscopy (TEM) measurements, it has been concluded that gold nanokites and nanotadpoles could be obtained by regulating the reaction time and the concentrations of chloroauric acid and PVP in the condition of using PVP as surfactant and water as solvent. The stable gold sol particles have been obtained by using KH-550 as surfactant and DMF as solvent. The result of TEM has showed that the gold nanoparticles could give spherical morphology.Silver nanoparticles have been synthesized by using PVP as surfactant, silver nitrate as precursor, ethanol, water and DMF as solvents respectively. It has been found that silver nanoparticles which were obtained at different reaction temperatures and reactant concentrations had different absorption spectra characteristics through UV-visible absorption spectrum and the kinetics of different reaction conditions. By using X-ray diffraction and transmission electron microscopy methods, it has been concluded that silver nanoparticles with good size distribution were obtained in three different reaction systems by using PVP as surfactant which played a good modification and limited the growth of silver nanoparticles.Copper nanoparticles have been synthesized on the interface of toluene and water (or water-ethanol) by using sodium oleate, octadecylamine as surfactants, DMF as reducing agent, copper nitrate as precursor according to the principle of interface reaction mechanism. It has been suggested that sodium oleate played a good modification on the surface of copper nanoparticles by the analysis of UV-visible absorption spectrum. The results show that the rod-like copper nanoparticles could be obtained at a certain concentrations of copper nitrate in the toluene/water two-phase system by TEM and XRD measurements.