Silver dendrites from galvanic displacement on commercial aluminum foil as an effective SERS substrate.

A silver galvanic displacement process on commercial aluminum foil has been carried out to produce cost-effective SERS substrates. The process is based on an extremely simple redox process where aluminum is oxidized while silver ions are reduced, yielding a final silver dendritic structure that offers a large surface area-to-volume ratio. XPS measurements confirmed the metallic nature of the formed dendrites. SERS substrates were fabricated by spreading of the dendrites on double side Scotch tape attached to a paper slide. Three different thiols were incubated to achieve SAM formation on the Ag dendrites and measured by Raman spectroscopy. The obtained spectra presented well resolved bands and provided valuable information regarding the orientation of the thiols. The high Raman intensity also demonstrates the high enhancement capacities of the produced silver structures. The overall method is cost-effective and allows the use of silver dendrite paste for the mass production of SERS-active substrates, including on flexible substrates and/or via screen printing.