Controlled Synthesis Of Silver Micro/Nano-particles

Silver micro/nano-particles are of great fundamental and industrial interest for their unique physical and chemical properties. Therefore, interest in the synthesis of silver micro/nano-particles has been growing steadily over the past decade. We begin with a brief introduction of the properties and the applications of silver micro/nano-particles, and then we focus on the controlled synthesis of silver micro/nano-particles with three different reductants, respectively. This work mainly includes the following aspects:Controlled synthesis of silver micro/nano-particles was investigated via a chemical route, in which ascorbic acid (Vc) was used as reducing agent, A1 was used as capping agent, and silver-amine complex was used as precursor. Uniform silver particles with the diameters ranging from 200nm up to 2000nm were obtained by varying the reaction conditions i.e. the dosages of aqueous ammonia and A1, the concentration of the reactants and the reaction temperature.Preparation of silver particles was studied via a chemical route, in which ascorbic acid was used as reducing agent, and A3 was used as capping agent. The analytical results indicate the optimum reaction conditions were as follows: 2.8g AgNO3, 3.0g Vc, 0.35g A3 and 0.2g alkali, and thus monodispersed spherical silver particles with the average size of ~800nm were obtained.Synthesis of silver micro/nano-particles were researched by a chemical route, in which formaldehyde was used as reducing agent, and A4 was used as capping agent. The analytical results indicate the optimum reaction conditions were as follows: 4.3g AgNO3, 10mL CH2O (37~40wt%), 0.17mL A4, 0.75g alkali, 37mLNH4OH (25~28wt%), and thus well-dispersed silver particles with narrow size distribution were obtained.Controlled synthesis of uniform micron-size silver particles were obtained by reducing silver nitrate with iron(II) sulfate heptahydrate in aqueous solution at room temperature. By varying the reaction conditions including reaction temperature, the absolute concentrations of the reactants and the molar ratio between silver nitrate and iron(II) sulfate heptahydrate, large flower-like silver particles with the size ranged from ~1mm up to ~4mm in diameter could be obtained.