The Preparation Of Graphene/pani Composites, The Electrochemical Properties And Mechanism Research

Grephene and polyaniline have excellent physical and chemical properties and show good prospect of application in various fields. Herein, three kinds of graphene oxides with different oxidation-reduction digree have been prepared. Their composites combined with polyaniline are synthesized via an in-situ polymerization, and exhibit the morphology of conducting fiber bridged structure. The morphology and structure of the products have been characterized with a transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction. The electrochemical performance and conductivity of the composites are studied using an electrochemical workstation and four-probe instrument. Gaussian03W software is used to explore the combining mechanism of graphene and polyaniline. The main results are as follows:(1) Functionalized graphene (G1) prepared by the modified Hummer’s method possesses plenty of oxygen-containing functional groups. The functionalized graphene of G2is synthesized through the elimination of the epoxy group of G1using sodium borohydride. The functionalized graphene of G3is fabricated by eliminating the hydroxyl group of G2using sulfuric acid.(2) The composite of GiP is synthetized by a in-situ polymerization in the different mixed media of ethylene glycol and water. The composite G1P15synthesized from the mixed solution of ethylene glycol and water (1:5in volume) shows a bridged structure with conducting polyaniline, and exhibits excellent electrochemical capacitance and electrical conduction. The specific capacitance of G1’P15is987.4F/g at the scan rate of5mV/s. The conductivity values of GiP15and G1’P15are2.03S/cm and0.71S/cm.(3) The composite of G2P, synthetized in of the mixture of isopropyl alcohol and water at ratio of1:5, shows the morphology of a bridged structure with the polyaniline wires. The specific capacitance of G2P is up to768.11F/g at the scan rate of5mV/s. The conductivity of G2P is2.41S/cm by the four-probe electrical conductivity testing. The result indicates that the composite has a good electrical conductivity.(4) The composite of G3P15, produced by adjusting the proportion of isopropyl alcohol and water, presents a bridged structure with polyaniline wires. The specific capacitance of G3P15is up to782.15F/g at the scan rate of5mV/s. The conductivity of G3P15is2.53S/cm by the four-probe electrical conductivity testing. The composite has good specific capacitance and excellent electrical conductivity. (5) The weak interaction between oxygen-containing functional groups of graphene and aniline has been explored by Gaussian03W. It is found that the weakly interaction between graphene and aniline is the most stable in the water system. The conclusion indirectly validates the previous experimental result, i.e., the composites of graphene and polyaniline with conducting polyaniline connection can be easily fabricated in the media with more water.