Preparation and Characterization of Graphene

Based on the Hummers method,the graphite oxide (GO) was prepared from the flake graphite through liquid oxidation;and then the graphene was prepared by using hydrazine hydrate to reduce the exfoliated graphite oxide nanosheets in the aqueous colloidal suspension.The structure and the thermal stability of graphite,graphite oxide and graphene were characterized by Fourier transform infrared spectroscopy (FT-IR),Raman spectroscopy (RS),X-ray diffraction analysis (XRD) and thermo-gravimetric analysis (TG),respectively.The results show that part of sp3-hybridized carbons in graphite oxide are reduced to sp2-hybridized carbons in graphene,and the average size of sp2-hybridized carbon layer surface of graphene is larger than that of graphite oxide,while the intensity of crystallization and the regularity of graphene are lower than that of graphite.Under our experimental conditions,the structure of the reduced graphite oxide can not be fully recovered to the original structure of the graphite before it forms graphite oxide;it means that the structure of graphene is different from that of graphite.The thermal analysis results indicate that the heat stability of graphene is much better than that of graphite oxide.