Monodispersed graphene quantum dots encapsulated Ag nanoparticles for surface-enhanced Raman scattering

We report our successful fabrication of graphene quantum dots shell-isolated Ag nanoparticles (Ag@GQDs NPs) which size was in the range of 40-80 nm. To the best of our knowledge, this is the first report to fabricate Ag@GQDs NPs of less than 100 nm in particle sizes, particularly with monodispersion characteristic and smooth surface. Transmission electron microscopy (TEM) images reveal that Ag NPs cores are completely encapsulated by 2-4 layers of GQDs. More importantly, Ag@GQDs NPs show a significantly higher Raman signal for the absorbed crystal violet molecules as compared to Ag NPs, suggesting that the Ag@GQDs NPs can act as a new type substrate for surface enhancement of Raman scattering (SERS) substrate.