Preparation Of Graphene By Sonication-assisted Liquid Exfoliation And Its Application

Graphene with high thermal conductivity,conductivity and specific surface area as two-dimensional material.It has many potential applications,such as in physics,chemistry and other fields.The large scale preparation of high quality graphene is still a bottleneck at low-cost,which the application of downstream industry.Because of the feature of simple process,low cost,high-yield,and others,preparation of graphene by exfoliating graphite in liquid become hotspot.In this paper,different kinds of graphite materials and liquid systems influence on the preparation of graphene were studied by ultrasonic assisted liquid phase exfoliation.The invention relates to the preparation of graphene by two methods: organic system and water system.The organic system is prepared by ultrasonic exfoliation of various pretreated graphite in toluene solution of polycarbazole and the preferred graphene is used in epoxy resin composite.The influence of four kinds of raw graphite materials on the quality and yield of graphene after intercalation and chemical expansion was studied.Two kinds of graphene were used as supercapacitor electrode materials,and their electrochemical performance was characterized.The main results are as follows: the experiment of preparation of graphene in organic system,the spontaneous-exfoliation TEG from sodium persulfate and concentrated sulfuric acid introduces a high oxidation defect and the stripping effect is not as good as TEG prepared as a precursor.When the ultrasonic output energy of TEG was 10 Wh/m L,the graphene concentration was about 25.58 ?g/m L,and the size of the monocrystalline graphene was about 2 ?m,the thickness was about 3 nm.The surface resistivity of the composites was 9.17×106 ?/square when the graphene was 0.5 wt.%,and with seepage behavior.In the experiments of preparation of graphene by aqueous phase system,NFG,GP-A and GP-B can be formed into three-order CrO3-GIC by chromium oxide intercalation,while TEG has no third-order CrO3-GIC characteristic diffraction peak obviously.The lateral size of FLG(NFG)and FLG(TEG)were significantly higher than those of FLG(GP-A)and FLG(GP-B)in the aqueous solution of sodium deoxycholate.Respectively,the yield of graphene reach to 20.7% and 12.3% were prepared with GP-A and GP-B,and the concentration reach to 0.26 mg/mL and 0.15 mg/mL in the NaDC/water solution,they have no visible subsidence after standing about two months.According to statistical analysis,the thickness of FLG(GP-A)less than 3 nm up to 78%,74% of the slice size between 1 and 6 ?m.The conductivity of the graphene papers were 0.96×104 S/m and 1.72×104 S/m,after FLG(GP-A)and FLG(GP-B)dispersions were filtered and washed,respectively.The electrochemical performance of the graphene papers were tested by three electrode method,both of them show the good capacitance characteristics of the electric double layer.