Synthesis And Characterization Of Graphene Based Nanocomposite For Supercapacitors

Graphene has the highest conductivity, abundant surface area and electron transfer property. In this experiment, it was used as a substrate to fabricate composites with the conductive polymer(PANI) through the assistance of surfactant via in situ polymerization method. Also, we synthesize two kinds of graphene/Fe3O4 nanocomposites via a colloid electrostatic self-assembly process, and study the properties of the synthesized materials as electrode materials for supercapacitor.First of all, Cubic-Fe3O4 nanoparticles were loaded and dispersed onto the surface of reduced graphene oxide(r GO) via a colloid electrostatic self-assembly process following hydrothermal treatment. The similar combination occured driven by the electrostatic force between the negatively charged GO sheets and positively charged Fe(OH)3 colloid nanoparticles. Cubic-Fe3O4@r GO composite(CFGC) was fabricated after treatment in autoclave and investigated as electrode material. TEM and SEM images distinctly showed that No alone cubic-Fe3O4 nanoparticle or r GO nanosheet is observed, which is roughly indicating the self-assembly process between the Fe(OH)3 colloidal nanoparticles and GO nanosheets. The CFGC exhibited a specific capacitance of 216.7 F/g in 6M KOH aqueous electrolyte at 500 m A/g.Secondly, poly(sodium 4-styrenesulfonate)(PSS) was used to decorate exfoliated graphite oxides(GO), than the well dispersed PSS functionalized graphene(PSS-Gr) was obtained via the in situ reduction. Just through this process, the Zeta potential on the surface of the graphene was changed, following via a colloid electrostatic self-assembly process, than dealing with the calcined under nitrogen atmosphere, finally Fe3O4@r GO composite(FGC) with different composition and morphology was prepared. The composition of graphene and ferroferric oxide(Fe3O4) can effectively improve the conductivity of the Fe3O4, and prevent the reunion of graphene. The results of SEM and TEM showed that Fe3O4 nanoparticals with an average diameter of about 25 nm were uniformly distributed on the translucent wrinkled surface of the Fe3O4@r GO. The FGC exhibited a specific capacitance of 197 F/g in 6M KOH aqueous electrolyte at 500 m A/g. The capacitance retention exceeded 87 % after 3000 cycles。Finally, Polyaniline/graphene(PANI/GN) nanocomposites were fabricated via in-situ oxidative polymerization of aniline in the presence of cetyltrimethylammonium bromide(CTAB) modified graphene(CGN). The results indicated that the graphene sheets disperse into the form of mono-layer or stack few layers in PANI matrix. The graphene sheets serve as a support material for PANI particles and the structure of graphene covered with PANI nanoparticles were confirmed by FE-SEM and TEM. Graphene with polyaniline formed three-mensional open porous structure, which is conducive to the diffusion of charged particles to the electrode interface to attend adsorption-desorption and electrochemical reaction. FT-IR and X-ray diffraction curve also shows that the polyaniline and graphene composite was successfully synthesized. Further electrochemical test results show that conductivity of the composite electrode was enhanced due to graphene, and then the performance of the fabricated capacitor was improved. When the capacitor was charged and discharged in 1M Na2SO4, the highest capacity is 233F/g.