Design And Application Of Electrode Based On New Graphene Nanocomposite

The development of nanotechnology offer new horizons for the application of nanomaterials in electrochemistry. Recent research interest has focused on the preparation of nanomaterials/nanocomposites involving the combination of graphene and conducting polymers. Graphene is a single-atom thick, two-dimensional sheet of sp2bonded carbon. Incorporation of graphene in the matrix with hydrophilic groups or molecules can improve water solubility, mechanical, thermal properties and enhance electrical conductivity of graphene. In this study, two novel graphene-based nanocomposites were prepared by different methods and applied in the field of electrochemistry. The contents of the thesis are shown as follows:1. The design and application of glucose biosensor based on the Graphene/Polyaniline/gold nanoparticles nanocomposite. Compared with graphene, polyanilline (PANI) or graphene/PANI, the graphene/PANI/AuNPs nanocomposite was more biocompatible and it offered a favorable microenvironment for facilitating the direct electron transfer between GOD and electrode. An apparent electron transfer rate constant (ks) is4.8s-1and the apparent Michaelis-Menten constant of the adsorbed GOD was0.60mM, implying a fabulous catalytic activity and remarkable affinity of the absorbed GOD for glucose. The amperometric response of GOD-graphene/PANI/AuNPs modified electrode was linearly proportional to the concentration of glucose in the range of4.0μM-1.12mM with a low detection limit of0.6μM at signal-to-noise ratio of3. The combination of the direct electron transfer character of GOD and the promising feature of graphene/PANI/AuNPs nanocomposite favors the selective and sensitive determination of glucose with improved analytical capabilities.2. The Graphene/Polyaniline/AuNPs/Glucose oxidase biocomposite:For the fabrication of paper-based analysis system. A convenient, fast, low cost, small sample volume and in situ method for the detection of glucose in human whole blood has been developed by using a disposable screen-printed carbon electrode (SPCE) in coupled with a paper disk. To perform the assay, the SPCE was modified with GOD-graphene/PANI/AuNPs biocomposite and then covered by a paper disk impregnated with sample. After introducing PBS on the paper disk, the electrochemical measurement was carried out by differential pulse voltammetry (DPV). The analytical performance was comparable to conventional methods. The sensor covered the full range of clinically relevant concentrations of glucose in whole blood. This new paper-based electrochemical glucose sensor shows promise for the fabrication of point-of-care (POC) device in whole blood tests.3. Graphene-based Titanium Nitride nanosheets as efficient electrocatalysts for simultaneous determination of4-aminophenol and acetaminophen, we developed a green and facile approach to the synthesis of chemically converted reduced graphene oxide (RGO) based on reducing sugars. The route for the efficient reduction and functionalization of GO suspension by glucose in the presence of Zn catalyst only needs30min. Based on the method, we prepared Titanium Nitride nanoparticle modified RGO (RGO/TiN). The obtained RGO and RGO/TiN hybrid materials are characterized with UV-visible absorption spectroscopy, transmission electron microscopy, Fourier transforminfrared spectrometry and so on. The merit of this method is that both the reducing agents themselves and the oxidized products are environmentally friendly. It should be noted that, besides the mild reduction capability to GO, the RGO/TiN nanocomposites exhibit good stability in water. This approach can open up the new possibility for preparing RGO and RGO-based hybrid materials in large-scale production alternatively. What’s more, the RGO/TiN composite film modified glassy carbon electrode (GCE) is fabricated and used to detect4-aminophenol (4-AP) and acetaminophen (ACOP). The electrochemical sensor shows a wide linear response for4-AP and ACOP in the concentration range of0.05-520μM and0.06-660μM with detection limit of0.013μM and0.02μM at S/N=3, respectively. These results demonstrate that RGO/TiN composite is a promising candidate of advanced electrode material in electrochemical sensing and other electrocatalytic applications.