The Synthesis Of Graphene And Graphene/polyaniline Composites

Graphene was first prepared based on micromechanical exfoliation in2004. Dueto its unique electronic, mechanical and optical properties, graphene (GE) hasattracted numerous investigations in academic and technological fields, such ascomposites, energy storage devices, et al. In general, the practical applications of GEmainly depend on the appropriate methods for its mass production. Usually, chemicalreduction of graphite oxide (GO), as one of the most promising approaches to prepareGE in large-scale, was carried out using hydrazine and sodium borohydride as thereducing agents. However, these agents are highly toxic and very unstable, thereforesome new and environment-friendly reducing agents to prepared GN in large-scale isurgent.In this thesis, we reported an efficient, environment-friendly and low-cost routeto synthesize soluble graphene nanosheets (GNS) with long-term dispersion stabilityin water and some common organic solvents. Furthermore, GE was applied tofabricate graphene/polyaniline composites (GNS/PANI) based on the in situpolymerization technique. The results mainly run as follows:1. GO was prepared based on Hummers and Modified Hummers methods. Theresult showed raw material had a more important effect on the preparation of GO, andGO synthesized by Modified Hummers had the best degree of oxidation usinggraphite flake. The result indicated that the d-spacing became larger after oxidation,and the polarity enhanced significantly. Furthermore, the sheets contained a largeamount of oxygen-containing functional groups.2. The optimum reaction conditions based on N-methyl-p-aminophenol sulfate(metol) reduction was obtained. Within only12min, exfoliated GO in ammoniasolution (pH10) was successfully reduced to prepare soluble GNS at95°C. Theresults revealed that most of the oxygen-containing groups were removed successfully,and the sp2carbon sites and ordered crystal structure are restored after reduction.Furthermore, metol or/and its oxidized products, absorbed on both sides of the GNS,have a significant effect on enlarging the thickness of the GNS.3. Metol was used to compare with hydrazine under the same reaction conditions.The result implied the deoxygenation efficiency of metol was matched with hydrazine in the chemical reduction of GO. Furthermore, the as-prepared GNS had a similarthermal stability. As a result, the reaction based on metol reduction could replacehydrazine in the mass production of soluble GNS.4. The reaction time based on metol reduction was examed at differenttemperature, and the activation energy was about88kJ/mol according to theArrhenius equation. Combined with the possible mechanism for the chemicalreduction, the reason why the reaction rate was so fast was also further explained. Onone hand, the reaction had low activation energy, on the other hand, the molecularstructure of metol contains amino and hydroxyl groups simultaneously, whichenhance the activity of the reducing agent significantly.5. Graphene/polyaniline composites (GNS/PANI) were prepared through in situpolymerization. The result showed that GNS could effectively charge the morphology,and GNS/PANI exhibited a better thermal stability. Furthermore, due to thereinforcement of GNS, the BET surface area and electrical conductivity of thecomposite are also increased markedly.