Synthesis of fluorescent graphene quantum dots from graphene oxide and their application in fabrication of GQDs@AgNPs nanohybrids and sensing of H2O2

Abstract Graphene oxide (GO) with hydrophilic properties supports the scalable production of highly desirable material graphene. GO nanosheets were prepared with a modified Hummers method, whereas the oxidative cutting technique was used to synthesize graphene quantum dots (GQDs). The surface and structural morphology of both GO and GQDs were examined and compared. In GO, photoluminescence originated mainly due to the conductive electrons present in the sp2 localized sites and the excimer formation. In contrast, in GQDs, PL is increased due to numerous defects present on their surfaces. The pH plays a crucial role in tuning the blue and green PL of GQDs hence the optical properties. The developed GQDs with functional groups act as a solo reducing and stabilizing agent in producing the GQDs-silver nanoparticles (GQDs@AgNPs) hybrid structure, which exhibits strong surface plasmon resonance along with GQDs absorption. Further, GQDs alone support sensing of hydrogen peroxide (H2O2) in an aqueous medium, thus acting as a sensing probe like the GQDs@AgNPs nanohybrids.