Synthesis of Monodisperse Au, Ag, and Au-Ag Alloy Nanoparticles with Tunable Size and Surface Plasmon Resonance Frequency

摘要

Metallic nanoparticles (NPs), especially silver and gold nanoparticles, are of great interest because of their unique optical and catalytic properties. In particular, the localized surface plasmon resonance (LSPR) of metallic NPs enables applications in many fields, including bioimaging, metamaterials, drug delivery/ cancer therapy, and surface-enhanced Raman scattering.' The LSPRfrequency is strongly dependent on the size, shape and composition of metallic NPs. Metallic NPs, especially gold and silver NPs, have been synthesized by many groups. However, improved methods for the synthesis of alloy nanoparticle and for the tuning of surface plasmon resonance through composition remain of interest. Alloying is also of interest for the control of other properties, such as catalytic activity. Gold and silver NPs typically have LSPR wavelength around 530 and 400 nm, respectively. These can be tuned to longer wavelengths by varying particle shape. For example, gold nanorods exhibit a longer wavelength LSPR corresponding to resonances along their longitudinal dimension. However, tuning of the LSPR frequency between 400 and 530 nm can most readily be achieved by producing Au—Ag alloy nanoparticles.