Bimetallic AgM (M = Pt, Pd, Au) nanostructures: synthesis and applications for surface-enhanced Raman scattering

Bimetallic nanoparticles exhibit unique optical and catalytic properties that are dependent on their composition, morphology and structure. In this work, a facile and effective approach, based on a galvanic replacement reaction and co-reduction method was developed to prepare bimetallic AgM (M = Pt, Pd, Au) nanoparticles with hollow or porous structures. The molar composition of Ag and the structure of AgM nanoparticles could be simply modulated by controlling the reaction time. The hollow or porous structure and bimetallic nature of the nanoparticles were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), and UV-vis spectroscopy. The morphology and phase of the bimetallic AgM nanoparticles were discussed as a function of reaction time. Due to the unusual structures, the bimetallic AgM nanoparticles exhibited interesting optical properties. Surface-enhanced Raman scattering (SERS) measurement showed that the SERS activity of the bimetallic AgM nanoparticles was dependent not only on the composition of the particles, but also on the structures (e. g., hollow or porous). The results indicate that as-synthesized bimetallic AgM nanoparticles are good candidates for SERS spectroscopy.