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.

Graphical abstractDendritic Ag-Pd bimetallic nanostructures were synthesized using a multi-stage galvanic replacement reaction method at 100 °C. These dendritic Ag-Pd bimetallic nanostructures exhibit high SERS activity and may have potential applications in investigating the surface chemistry in a particular reaction using SERS, for example, “in situ” Pd catalytic reactions.Download full-size imageHighlights► Dendritic Ag-Pd bimetallic nanostructures were synthesized using a multi-stage galvanic replacement reaction method. ► Dendritic Ag-Pd bimetallic nanostructures together with the Cu substrate can be directly used as SERS substrate to probe molecules. ► The dendritic Ag-Pd bimetallic nanostructures exhibit high SERS activity.