Fast and green synthesis of flexible free-standing silver nanoparticles–graphene substrates and their surface-enhanced Raman scattering activity

Abstract

A fast and green way to synthesize a free-standing and flexible silver nanoparticles–graphene (Ag NPs–GE) film with high surface-enhanced Raman scattering (SERS) sensitivity has been developed. The silver nitrate–graphene oxide (Ag+–GO) films can be fabricated through vacuum filtration of the Ag+–GO suspension. And then, through the thermal annealing under H2/Ar atmosphere at 400 °C, as-synthesized Ag+–GO films were thermal reduced to Ag NPs–GE films. The SERS activity of these substrates was greatly influenced by different laser wavelengths. And the maximum enhancement factor value for the Raman signals of R6G adsorbed on Ag NPs–GE substrate obtained at 780 nm (1.25 × 107) was much larger than that acquired at 532 nm (3.7 × 105). Furthermore, the high mechanical and flexibility of the GE sheets can provide protection of Ag NPs from the surrounding environment to yield a high degree of temporal stability.