Silver nanoparticles aggregate on passivated copper foil for Surface-enhanced Raman scattering

Surface-enhanced Raman scattering (SERS), as a powerful tool of chemical and biological analysis, has been investigated extensively in recent years. In this work, the reduction of silver nitrate by copper foil in aqueous medium was used to prepare silver nanoparticles and a method of applying ultrasonic to passivate the copper foil in the sulfuric acid solution was proposed in order to regulate the deposition of the Ag nanoparticles. Analysis of the surface structure by a fieldemission scanning electron microscope (FESEM) revealed that the silver nanoparticles deposited on the passivated copper foil were more regular. SERS spectra of Rhodamine6G (R6G) adsorbed on these Ag-Cu substrates were studied and compared. It´s found that the Ag-Cu substrate prepared with the Cu foil passivated by ultrasonic treatment has a significantly higher Raman signal sensitivity, better large-area uniformity, and 80% of original sensitivity was remained in 10 days of storage time in the air, indicating the substrates are fairly stable.