In situ decoration of plasmonic silver nanoparticles on poly(vinylidene fluoride) membrane for versatile SERS detection

A new strategy based on a polymer sol was proposed for the in situ fabrication of a poly(vinylidene fluoride) (PVDF) membrane decorated with silver nanoparticles (AgNPs) for application in surface enhanced Raman scattering (SERS). The reduction of Ag(I) in a PVDF sol and the phase inversion of the PVDF membrane were performed simultaneously during the formation of the AgNPs/PVDF membrane. The plasmon resonance features of the AgNPs provide the AgNPs@PVDF membrane with the potential for use as a SERS substrate with negligible background interference following Raman laser excitation. Meanwhile, the properties of the high-viscosity polymer can reduce the diffusion of Ag(I) and prevent the agglomeration of Ag nanoparticles, which potentially contributes to the high SERS activity of the AgNPs@PVDF membrane. The effect of the Ag(I) concentration on the size and distribution of the AgNPs on the membrane surface and the corresponding SERS activity have been investigated. The AgNPs/PVDF membrane decorated with 2.5 wt% Ag presents a high SERS activity and good reproducibility. It also has a sensitive SERS response for 4-NTP molecules with an enhancement factor of 2 x 10(6) and a low detection concentration of 1 x 10(-10) mol L-1. Moreover, the portable and easily-prepared AgNPs@PVDF membrane has potential for the direct detection of Cd(II) owing to the concentration-dependent Raman response.