Facile preparation of dendritic Ag–Pd bimetallic nanostructures on the surface of Cu foil for application as a SERS-substrate

Dendritic Ag–Pd bimetallic nanostructures have been synthesized on the surface of Cu foil via a multi-stage galvanic replacement reaction (MGRR) of Ag dendrites in a Na2PdCl4 solution. After five stages of replacement reaction, one obtained structures with protruding Ag–Pd flakes; these will mature into many porous structures with a few Ag atoms that are left over dendrites. The dendritic Ag–Pd bimetallic nanostructures were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS). The morphology of the products strongly depended on the stage of galvanic replacement reaction and reaction temperature. The morphology and composition-dependent surface-enhanced Raman scattering (SERS) of the as-synthesized Ag–Pd bimetallic nanostructures were investigated. The effectiveness of these dendritic Ag–Pd bimetallic nanostructures on the surface of Cu foil as substrates toward SERS detection was evaluated by using rhodamine 6G (R6G) as a probe molecule. The results indicate that as-synthesized dendritic Ag–Pd bimetallic nanostructures are good candidates for SERS spectroscopy.