Controlled synthesis of icosahedral gold nanoparticles and their surface-enhanced Raman scattering property

The aqueous-phase synthesis of icosahedral gold nanoparticles with controlled diameters ranging from 10 to 90 nm is reported. The nanoparticles were prepared by a seed-mediated growth approach. Citrate-capped 3.5 nm gold nanoparticles, prepared by reduction of HAuCl4 with sodium borohydride, are used as seeds. Cetyltrimethylammonium bromide molecules served as a capping agent to restrict the nanoparticles size. The synthesized gold nanoparticles were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy, and X-ray diffraction (XRD). The crystal structure of the particles was found to consist of mostly {111} surfaces as revealed by both TEM and XRD results. The prepared icosahedral gold nanoparticles show efficient surface-enhanced Raman scattering properties.