Surface-enhanced Raman scattering (SERS)-active substrates of polyvinyl alcohol/gold–silver (PVA/Au–Ag) nanofibers were prepared using a simple approach involving electrospinning. The tunable surface plasmon resonance (SPR) of gold–silver alloy (Au–Ag alloy) nanoparticles (NPs) was achieved by controlling the feed ratio between gold and silver precursors. A higher concentration of Au–Ag alloy NPs could be obtained than the conventional methods, using 1 wt% of PVA as the stabilizer. The Au–Ag alloy structure was demonstrated by HRTEM and STEM-EDX. After the electrospinning, the Au–Ag alloy NPs were successfully embedded in PVA nanofibers, as shown in the SEM and TEM images. Raman spectra displayed an apparent enhancement in the signal of 4-mercaptobenzoic acid (4-MBA), pyridine, and thiophenol molecules pre-absorbed from their ethanol solution onto the PVA/Au–Ag nanofibers. Different SERS effects were achieved by varying the Au content or excitation wavelength.
