Electrophoretic deposition (EPD) of silver nanoparticles and their application as surface-enhanced Raman scattering (SERS) substrates

Surface-enhanced Raman scattering (SERS) substrates were obtained by electrophoretic deposition (EPD) of silver nanoparticles with different morphologies. The silver nanoparticles were prepared by chemical methods in aqueous dispersion. Silver nanospheres, triangular nanoprisms and nanodisks were deposited on vertically aligned copper plates in an electrophoretic cell. The silver nanoparticles were deposited using a constant applied voltage of 300 mV, 600 mV and 900 mV for 24 h. Silver thin films porosity can be tunable varying the strength of the applied electric field. The resulting high porosity provides a high surface area for adsorption of analyte molecules, which increases the number of molecules available for Raman analysis. The analytical enhancement factors of the silver SERS substrates prepared at 300 mV were determined using rhodamine 6G (R6G) as analyte. The analytical enhancement factors of the fabricated SERS substrates are about 103–104, which are enough to detect analytes at concentrations below 1 ppm. This study provides a green, simple, low-cost and large-area methodology for the fabrication of SERS substrates.