Preparation Of Graphene-Based Composite Materials And Their Electrochemical Performance

The development of chemical modified electrodes(CME) opened a new area of research in electrochemistry fields. They are suitable for application in electrocatalysis, biosensors, selective electrochemical analysis. Graphene, with a two-dimensional one-atom-thick planar sheet of sp2bonded carbon atoms, is endowing the carbon materials for potential application in electrocatalysis, hydrogen storage and supercapacitors with various superior properties such as large specific surface area(2630m2/g), high electrical conductivity (200,000cm/V·s) and charge-carrier mobility, high mechanical strength and inherent flexibility. Research on the graphene modified electrodes began very recently and rapidly gain attention due to the outstanding properties of graphenes. In this paper, N-doped graphene was prepared by solvothermal reaction with graphene oxide and ethylenediamine. The N-doped graphene modified electrode is highly sensitive and selective toward the detection of ascorbic acid. The PB/graphene oxide nanocomposites were prepared by simple refulx reaction routes. The PB/graphene oxide-modified electrode showed good electrocatalytic activity toward hydrogen peroxide reduction.On the based of the excellent electrocatalytic effect of the graphene nanoplatelets modified electrode (GHNP/GCE) toward the electrochemical reaction of ascorbic acid, a new method for electrochemical determination of ascorbic acid was established. Compared with the bare glass carbon electrode (GCE), the graphene modified electrode pronounced the anodic peak currents response and lower the overvoltage and improved the sensitivity of determination. A voltammetric linear response for ascorbic acid was obtained in the concentration range of5.0×10-5mol/L～2.5×102mol/L and a detection limit(3σ7slope),6.5×10-7mol/L.N-doped graphene was synthesized by on-pot hydrothermal process in the mixed solution using ethylenediamine and graphene oxide (GO) as precursors. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) were utilized to characterize structure and electrochemical behavior of the as synthesized N-doped graphene. The organic amine is not only as reductant to remove the oxygen-containing groups (OCGs) in the graphene oxide, but also as nitrogen sources to obtained the N-doped graphene. The EIS revealed the electron transfer impedance of the N-doped graphene is obviously lower than graphene, indicating that the introduction of nitrogen-containing groups remarkably improve the electrical conductivity. The obtained N-doped graphene was also applied to electrochemical determination of ascorbic acid. The detection limit was found to be1.7×10-7mol/L. This demonstrated the material is of excellent electrocatalytic property.A facile and green method for the synthesis of different ratio of graphene oxide (GO)/prussian blue(PB) nanocomposites has been presented via a redox reaction in the80℃reflux containing Polyvinylpyrrolidone(PVP), K3[Fe(CN)6] and graphene oxide. PVP can reduce ferric iron. The obtained composite nanomaterials were characterized by TEM, XRD, FT-IR and electrochemical techniques. It was found that uniform PB with controlled size and good dispersion were directly grown on the surface of graphene oxide nanosheets. Moreover, we also investigated the performance of GO/PB nanocomposites as amperometric sensor toward reduction of H2O2. The ratio of1:2GO/PB/GCE showed a rapid and highly sensitive response to H2O2with a low detection limit of1.24×10-7mol/L (S/N=3).The modified electrode has a good stability and anti-interference ability.