Preparing silver nanoparticles in supercritical water

Silver (Ag) nanoparticles were prepared using Ag microparticles as precursors in supercritical water (SCW). The effect of reaction time on preparing Ag nanoparticles was investigated. The obtained products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The results indicated that, with the increase of reaction time, Ag microparticles prepared by calcination method with the sizes > 2 μm remained after SCW treatment because of their high crystallinity, but those with the sizes < 1 μm were destroyed and formed many Ag nanoparticles due to the destructive effect of SCW.