One-Pot Aqueous Synthesis of Fe and Ag Core/Shell Nanoparticles

This article investigates a facile one-pot method for the synthesis of Fe and Ag core/shell nanoparticles by aqueous reduction under ambient conditions. We have shown that the injection time of silver nitrate into a reaction vessel containing aqueous ferrous salt, sodium borohydride, and sodium citrate is a vital parameter for the precise control of a desired core/shell structure. For example, if silver nitrate is injected one minute after sodium borohydride is added to the reaction vessel, Ag will nucleate first followed by Fe, creating monodisperse Ag/Fe core/shell nanoparticles. In contrast, if the introduction time is prolonged to 5 min, Fe nanoparticles will nucleate followed by Ag producing Fe/Ag nanoparticles. The composition, morphology, and magnetic behavior were investigated by X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and room-temperature vibrating sample magnetometry (VSM). Fe/Ag core/shell nanoparticles with optical and magnetic functionality offer broad opportunities in medicine, catalysis, and chemical detection.