Synthesis And Electrochemical Properties Of 3D Graphene And Graphene-Based Composites

With the discovery of graphene to people, the researchers found that it posses many excellent properties in theory, such as a well of physics and many fascinating physical and chemical properties. There is a wide range of potential applications of graphene for two-dimensional(2D) atomic crystal materials. However, it has not totally been shown in practice, which because of the defects for structures.Three-dimensional graphene(3DRGO) has more excellent electrical conductivity and more outstanding propeties, such as large surface area and 3D cross-linked porous structure. And composite materials not only own the basic properties of graphene sheets, but also exhibit synergistic effects between different materials. In this paper,according to the good capability of electronic transmission of graphene, 3DRGO and grapheme-based nanocomposites were prepared by using solvothermal method, their electrochemical properties were studied. The main contents are as follows:1 Reduced graphene oxide(RGO) were prepared by using Na2S2O3 reduction graphene oxide from one-pot hydrothermal method. And 3D grapheme(3DRGO)were obtained by using Na2S2O3 as reducing agent and also through one-pot hydrothermal method, then dealed with freeze-drying. The products were characterized by XRD, SEM, FT-IR and TGA. The supercapacitor performanceand for materials were tested by electrochemical methods. The supercapacitor performance of 2DRGO and 3DRGO electrode was compared. The results of electrochemical tests show the specific capacitance of 3DRGO was higher than the2 DRGO. After 1000 cycles, specific capacitance of 3DRGO was 169.88 F·g-1, which the capacity holding rate was 70.40% of the initial value. It demonstated that 3DRGO has good cycle performance.2 One-pot hydrothermal process was used for preparing Nb2O5-RGO from thermally exfoliated grapheme oxide as precursor and NbCl5 as the source of niobium.The products were characterized by SEM, EDS, XRD, FT-IR and TGA, and then used for electrochemical test to research the supercapacitor performance. The supercapacitor performance of RGO and Nb2O5-RGO electrode was compared. The results of electrochemical tests show the specific capacitance of Nb2O5-RGO composites was higher reached 285.58 F·g-1. After 1000 cycles, its specific capacitance was 195.98 F·g-1, which the capacity holding rate was 68.60% of the initial value. It is obvious that Nb2O5-RGO nanocomposites exhibits excellent supercapacitive behaviors.3 MoO3-reduced graphene oxide(Mo O3-RGO) nanocomposite was prepared by a facile approach of one-step solvothermal method. The obtained MoO3-RGO nanocomposite was characterized by SEM, FT-IR, Raman, XRD and TGA, and then used to modify the glassy carbon electrode(GCE). The electrochemical behavior of baicalin on the unmodified GCE, RGO modified GCE(RGO/GCE), MoO3 modified GCE(MoO3/GCE) and Mo O3-RGO nanocomposite modified GCE(Mo O3-RGO/GCE)are compared. Mo O3-RGO nanocomposite has been proven to remarkably sensitivity and selectivity for baicalin. The current value of oxidation peak for baicalin was markedly improved after the glassy carbon electrode was modified by MoO3-RGO nanocomposite. After 90 s under open circuit, the linear range was from 1.0×10-9~4.3×10-5 M, and the detection limitation for baicalin was as low as 3.81×10-10 M. The average recovery ratio of baicalin was 100.27% by this analysis method.4 The nanocomposite of Fe2O3-reduced graphene oxide(Fe2O3-RGO) was synthesized by a hydrothermal reduction using Fe(OH)3 colloidal suspension and graphene oxide(GO) as precursors. The resulting composites were characterized using XRD, SEM, FTIR and TGA, and then were used to modify the glassy carbon electrode(GCE). The electrochemical behavior of honokiol and magnolol on the unmodified GCE, RGO modified GCE(RGO/GCE), Fe2O3 modified GCE(Fe2O3/GCE) and Fe2O3-RGO composite-modified GCE(Fe2O3-RGO/GCE) were compared. The Fe2O3-RGO/GCE enhanced electrochemical catalysis effect on the simultaneous determination of honokiol and magnolol. The current value of oxidation peak for honokiol and magnolol was markedly improved after the glassy carbon electrode modified by Fe2O3-RGO nanocomposite. A sensitive and simple electrochemical method was proposed for the simultaneous determination of honokiol and magnolol. The two well-shaped oxidation peaks were separated absolutely,which eliminated the disturbance between them. After 60 s under open circuit, as to honokiol, the calibration curve is from 1.5×10-8 to 3.3×10-5 M, and the detection limit is 9.64×10-9 M. For magnolol, the linear range is from 7.5×10-8 to 2.6×10-5 M, and the detection limit is 1.05×10-8 M.