Synthesis and Surface-Enhanced Raman Scattering Properties of AU@AG Core-Shell Nanoellipsoids

Abstract

This Seed-mediated growth prepared Au nanorods (Au NRs) are primarily secondary grown into Au nanoellipsoids (Au NEs) and then use as seeds for the epitaxial growth of silver shells on the gold core to form Au@Ag core-shell nanoellipsoids (Au@Ag core-shell NEs) in the presence of surfactants. The characterization of the morphology, optical properties and crystallography of Au NRs, Au NEs and Au@Ag core-shell NEs have been studied. Then we analyze the overall growth mechanism of the nanoparticles during the synthesis process. Moreover, by adjusting the amount of AgNO₃adding in the epitaxial processes, different size Au@Ag core-shell NEs can also be obtained. Additionally, the surface-enhanced Raman scattering (SERS) enhancing properties of Au@Ag core-shell NEs have also been evaluated with 4-mercaptobenzoic acid (4-MBA) labelled molecule as Raman detector. Interesting, such core-shell NCs also exhibit efficient SERS intensity. The results obtained here suggest that Au@Ag core-shell NEs might serve as nanoprobe for SERS-based analytical and biosensing applications.