Synthesis of reduced graphene oxide using indole as a reducing agent and preparation of reduced graphene oxide-Ag nanocomposites

Reduced graphene oxide has been successfully prepared via chemical reduction of graphene oxide by indole as a previously unreported reducing agent. The obtained single layer reduced graphene oxide, with an average thickness of 1.7 nm, is dispersible in organic solvents such as ethanol, N,N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide, tetrahydrofuran and isopropanol. Several analytical techniques including X-ray diffraction, UV/vis spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy have been used to characterize the resulting reduced graphene oxide, which indicates that most of oxygen functionalities are removed and yielding C/O ratio as high as 7.4. We further have demonstrated the subsequent decoration of reduced graphene oxide by direct adsorption of negatively charged Ag nanoparticles. It was found that the average diameter of Ag nanoparticles on the surface of reduced graphene oxide is between 20 and 40 nm. Furthermore, the intensity of Raman signals of reduced graphene oxide-Ag nanoparticles is about 21-fold by decorating with Ag nanoparticles, in comparison with reduced graphene oxide showing surface-enhanced Raman scattering activity.