Preparation of Silver Nanoparticles/Graphene Composite Films by Dip-Coating Method and their Surface-Enhanced Raman Scattering Property

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Recently, noble metal nanoparticles (Au or Ag NPs) decorated graphene (GE) sheets are used as good surface-enhanced Raman scattering (SERS) substrates for detection of molecules. Ultrathin GE film covered by Ag NPs has been designed for the SERS substrate in this paper. The films were prepared firstly by dip-coating method with graphene oxide (GO) and AgNO3 or Ag NPs colloid as raw materials and secondly reduced by thermal annealing at 600 °C in H2/Ar atmosphere. The structure and SERS activity of the obtained films have been investigated in detail. Results indicated that Ag NPs can be decorated on graphene sheets through the electrostatic adsorption between the GO sheets and positively charged Ag+ or Ag NPs. Compared with the film obtained with AgNO3, Ag NPs/GE film prepared with Ag NPs colloid showed the higher SERS sensitivity with rhodamine 6G (R6G) as the probing molecules, the enhanced factor for 1×10-5 M of R6G adsorbed on the surface of Ag NPs/GE substrate is about 9.1×107.