Synthesis Of Graphene(Composite) By ?-ray Irradiation Method

Due to the unique photoelectric properties,high specific surface area and excellent mechanical properties,much attention has been attracted by graphene.However,the agglomeration of graphene sheets,because of strong van der Waals and ?-? attraction between individual graphene sheets,seriously suppress graphene's intrinsic properties,limiting its application in many fields.Many efforts have been made to tackle this challenge:1)evenly load nanoparticles on graphene sheets to prepare nanocomposites,nanoparticles separating graphene sheets well;2)individual graphene sheets are bonded together to construct three-dimensional graphene networks.Typical synthetic methods of graphene and composites include chemical vapor deposition,chemical reduction and hydrothermal methods,the application of which is greatly limited by the high cost,the use of toxic reducing agents and harsh high pressure conditions.In this paper,we study the y-ray irradiation method in the preparation of two kinds of graphene-based materials.1.we have demonstrated a ?-ray irradiation reduction method to synthesize MnO/rGO composites conducted at room temperature and pressure.The y-ray irradiation generated · eaq-produces homogeneously distributed MnO with finely tuned particle size on rGO without the assistance of surfactant.The MnO/rGO composites outputs a reversible gravimetric capacities of 2175 and 775 mA h g-1 with respect to the mass of the whole composite at current densities of 0.2 and 8 A g-1,respectively,displaying an outstanding rate capability for the anode of lithium ion battery.The MnO/rGO composite enables a fully charge/discharge in 2 min to gain a reversible specific capacity of 546 mA h g-1 which is 45%higher than the theoretical value of commercial graphite anode.2.We have displayed a gentle y-ray irradiation method to prepare graphene sponge without the use of surfactant.To analyze the influence condition on the formation of sponge structure,we explore the dispersion of GO by adjusting pH with adding acetic acid and ammonia.Interestingly,we can enhance the compressive properties of the graphene sponges by adding 5 wt.%CNT throughout the graphene sheet with the loading of 1.1 × 104 cm cm-2.The morphologies and density of graphene sponge can be controlled by adjusting pH of dispersions and the concentration of GO.The resultant sponge(GCS)show ultralow density(5.0 mg cm-3),high porosity(99.8%),great conductivity(0.012 S cm-1)and excellent compression performance(800 cycles at the strain of 50%).Furthermore,the length of the linear part of GCS is about 73.5%under the strain of 80%and the resistivity decreases(increases)linearly with the increase(decrease)of strain,which make GCS great candidates for elastic conductors,pressure-responsive sensors and other applications.