Synthesis of silver nanoparticle through a bromide mediated polyol method

Silver nanoparticles (AgNPs) have been widely used in various fields of science because of their unique optical and chemical properties which depend on their size and shape. Synthesis methods are continuously being developed to control their size and shape. Synthesis using the polyol method allows to modification and control of the shape and size of AgNPs in a simple way and with readily available materials. In this research, AgNPs were synthesized using the polyol method using ethylene glycol (EG) as a reaction medium and reducing agent poly (vinylpyrrolidone) (PVP, Mw: 55,000) as a capping agent, and silver nitrate (AgNO3) as a precursor with the addition of Natrium Bromide (NaBr) as an additive. Here the concentration of AgNO3 and NaBr was varied to control either size or morphology of AgNPs. The resulted AgNPs were characterized using UV-vis spectrophotometer, Transmission Electron Microscopy (TEM), and X-Ray Diffraction (XRD). The UV-vis spectra data show that the concentration of NaBr affected the reduction rate of Ag+ to Ag0. As the concentration of NaBr increases, its reduction rate was also found to increase which was ascribed due to the formation of the nucleus through the heterogeneous nucleation process of AgBr. That observation also was supported by the XRD data showing the formation of AgNPs and AgBr crystal structures. Meanwhile, the TEM results indicate the formation of AgNPs with varying size and morphology depending on the concentration of NaBr and AgNO3 precursor.