Synthesis of monodisperse Ag–Au alloy nanoparticles with large size by a facile fabrication process

The fairish monodisperse Ag–Au alloy nanoparticles (NPs) with various composition and size were synthesized by a facile fabrication procedure. UV–visible (UV–vis) spectroscopy and transmission electron microscopy (TEM) confirmed the formation of homogeneous alloy NPs. The diameters of the resultant monodisperse spherical Ag–Au alloy NPs are 21–32 nm and the long-axis size of the resultant monodisperse nonspherical Ag–Au alloy NPs are about 28 nm. The possible formation mechanism is suggested by analyzing the dynamic absorption spectra, TEM and energy dispersive X-ray (EDX) spectroscopy of the alloy nanoparticles at the different time. Ag–Au alloy NPs synthesis method developed in this paper has several advantages: (1) the synthesis process is very simple. Only sodium citrate was used as both reducing agent and stabilizing agent and only one step heating process was needed. (2) The resultant Ag–Au colloidal dispersion is free from AgCl deposition and (3) the fairish monodisperse and large size (>20 nm) Ag–Au alloy NPs can be obtained.