Study on Optimization of Nano-silver Prepared by Method of Liquid Reduction

Objective The various influencing factors in the process of nano-silver preparation were studied in order to prepare nano-silver that has uniformity particle size distribution and good crystallinity. Methods Through the method of liquid reduction at room temperature,the nano-silver powders were prepared directly using silver nitrate as raw material,water as the reactive medium,polyvinylpyrrolidone(PVP) as protecting agent and ammonium formate as reducing agent. By means of EDS and TEM(transmission electron microscopy),the prepared silver particles were characterized. The various influencing factors in the process of preparation were also discussed. Results With the increasing concentration of AgNO3,the particle diameter of nano-silver changed obviously. When the concentration of silver nitrate was 0.25-0.30 mol/L,the size of product is the smallest. With the increasing concentration of reductant,the diameter of nano-silver decreased gradually. While at the concentration of 0.70 mol/L HCOOH,the average diameter of nano-silver is not more than 10 nm. Smaller and more well-distributed silver powder could be prepared at ratio of concentration of PVP to AgNO3 with the value of 1.5-1.0,at which PVP presented effective protection. Conclusions This method can prepare particle of nano-silver which revealed well dispersed and uniform size. The process is stable and reliable,easy to operate,high yields and suitable for industrial production.