Preparation, Characterizetion And Mechanism Of Graphene

Aim at the disadvantages of preparation method of graphene by oxidation reduction and the character of samples in the reaction very significant for studying the crystal chemistry of minerals, modification,organic treatment and crystal physics. So the preparation of graphene and the character of crystallography are studied in the paper.The crucial factors affecting the synthesis of graphite oxide is optimized by orthogonal test. graphite oxide with small structural defect and complete intercalation are prepared. graphite oxide is modified with a series of alkyl quaternary ammonium salt in the same experimental condition to get different intercalated graphite oxide; The effects of the chain length and dosage of alkylquaternary ammonium salt on the interlayer space of graphite oxide is also tested. Graphite oxide and modified graphite oxide are dealed with by ultrasonic delamination in water and organic solvents to produce a stable hydrosol of graphene oxide sheets. The colloidal form of graphene is subsequently prepared time in the presence of hydrazine hydrate. The factors affecting reduction degree and stability of graphene are discussed in reduction process, such as hydrazine hydrate dosage, reaction time and pH value in system. A stable hydrosol of graphene is synthesized by oxidation reduction and then a flow assembly of this graphene is used to form a graphene-based membrane by vacuum extraction filtering method.X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, particle size analysis, Ultraviolet-visible spectroscopy(UV-Vis) and scanning electron microscopy(SEM) are used to characterize the crystal structure, granularity, and characteristic change of the molecular spectrum of the samples in the reaction.The experimental results indicates that the optimized conditions for preparing graphite oxide with small structural defect and complete intercalation are conducted by increasing the mesothermal reaction temperature. The structural layer of graphite, during the oxidation process bonds to a large number of functional groups and increases in thickness. At the same time, the structural defect of graphite oxide increases, which resulted in increasing in the degree of disorder.The particle sizes of the graphene oxide sheets dispersed in water show a tailing peak and a broad distribution while the graphene sheets show a singlet, narrower distribution, and smaller dimensions. Graphene oxide and graphene can readily form stable aqueous colloids in water in alkali solution with uniform sheet thickness of 1nm. the structural characteristics of graphene oxide membrane gained by vacuum extraction filtering method is just as similar as that of graphite oxide. parts of these stable functional groups remain on the reduced structural layer of graphene. Suspensions of graphene oxide form condensed matter and graphene flocculating constituent during film deposition. the degree of sample disorder increases.On the basis of the above analyses, the structural characteristics of the samples in the reaction are summarized.