Large Scale Preparation Of Graphene Oxide Quantum Dots And Tunable-photoluminescence

Graphene quantum dots(GQDs) as the latest number of graphene family is a new kind of zero dimensional carbon based nanomaterial. Due to the pronounced quantum confinement, edge effects and size effects, GQDs not only possess numerous chemical/physical properties of graphene, also assume low cytotoxicity, excellent solubility,chemical inertia and stable photoluminescence, thus making them promising in optoelectronic device, bioimaging, sensors etc.In this paper, we mainly research the acid oxidation method to prepare GQDs and tune the optical properties by modifying the surface functional groups.1. The preparation and characterization of GQDsAcid oxidation method is a facile synthetic route that commonly used for the preparation of graphene oxide(GO). It includes Brodie, Staudenmainer and Hummer three ways. And compared with the other two methods, the Hummer method is widely used in the synthesis of GO as its simplicity, low pollution and safety. We use graphite as the starting material and adjust some steps of Hummer method. After two means of acid oxidation and high temperature crushing, we finally get the GQDs with high efficiency. The surface of GQDs prepared by this method is rich in oxygen functional groups which offer a high activity and make it possible for further decoration.2. The surface modification of GQDsUnder alkaline conditions, a simple hydrothermal reaction is carried out with a large number of the oxygen groups of graphene quantum dots, and control the ammonia and temperature we can vary the molecular weight and the special edge of the graphene quantum dots. When a certain excitation light irradiate the solution, the color of photoluminescence translate from blue and green to yellow and the maximum quantum yield can reach 20.4%.