In situ green synthesis of silver-graphene oxide nanocomposites by using tryptophan as a reducing and stabilizing agent and their application in SERS

Silver-graphene oxide (Ag-GO) nanocomposites were in situ fabricated rapidly through a green one-pot method by using tryptophan (Trp) as a reducing and stabilizing agent. The morphologies of synthesized Ag-GO nanocomposites were characterized by UV-vis absorption spectroscopy, transmission electron microscopy (TEM), and micro-Raman system. The results indicated silver nanoparticles (Ag NPs) with spherical size were well dispersed on the surface of graphene oxide (GO). The role of pH has been explored to obtain optimum reaction conditions during the growth process. Raman signals of GO were greatly enhanced after Ag NPs loaded on its surface. More importantly, the synthesized Ag-GO nanocomposites exhibited excellent surface-enhanced Raman scattering (SERS) activity as SERS substrates to detect crystal violet (CV) in aqueous solution, and the enhancement factor (EF) from the intensity of the vibrational mode at 1621 cm−1 was calculated to be 1.6 × 105.