Synthesis of tin oxide-coated gold nanostars and evaluation of their surface-enhanced Raman scattering activities

Tin oxide-coated gold nanostar hybrid nanostructures are prepared by first synthesizing gold nanostars (ca. 400 nm), then introducing Na₂SnO₃ precursor followed by its hydrolysis and formation of a tin oxide layer on nanoparticle surface. The synthesized hybrid structures have been characterized by combination of UV–Vis spectroscopy, transmission electron microscope (TEM), energy-dispersive X-ray studies, scanning electron microscope (SEM), X-Ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The TEM and SEM analyses showed that gold nanostars have a coating with an approximate thickness of 15 nm. The tin (IV) oxide coating on the gold nanostars was identified by XRD and XPS analyses and confirmed by FTIR spectroscopy. Surface-enhanced Raman scattering (SERS) spectroscopy was performed on tin oxide-coated and uncoated gold nanostars with crystal violet as a probe molecule. The SERS studies revealed field enhancement properties of Au nanostars, thus their strong SERS activity remained after tin oxide coating.