Preparation Of Novel Graphene Composite Materials And Their Applications For Electrochemistry

Graphene is a kind of novel two-dimensional carbon material. Due to its excellentmechanics, electronic, opticical and thermal properties, it has been one of the “hot spots” inmaterial science. However, the reduced GO has a tendency to agglomerate irreversiblythrough van der Waals interactions in the absence of a polymer dispersant or surfactant, whichrestrict its further research and application. In this study, we are dedicated to the study ofsimple and feasible method of preparation graphene and its applications in electrochemicalbiosensors. The dissertation is mainly focused on:1. A novel graphene-polydopamine nanomaterial with biomimetic functions wassynthesized. The graphene-polydopamine nanomaterial was applied in the fabrication of H₂O₂biosensors using hydroquinone as electron mediator. The modified electrode exhibited goodelectrocatalytical activity toward H₂O₂. The linear range was from5.0×10^-7to3.3×10^-4molL^-1with a detection limit of3.7×10^-7mol L^-1.2. Asimply and high selective electrochemical method for simultaneous determination ofhydroquinone （HQ） and catechol （CC） was developed at a glassy carbon electrode modifiedwith graphene-polydopamine （GN-PDA）. The separation of oxidation peak potentials for HQand CC was about103mV. In the presence of5.0×10^-5mol L^-1isomer, the oxidation peakcurrents was linear to the concentration of CC in the range of1.0×10^-6to2.5×10^-4mol L^-1with the detection limit of7.4×10^-7mol L^-1and to that of HQ in the range of1.0×10^-6to2.3×10^-4mol L^-1with the detection limit of6.2×10^-7mol L^-1. The calibration curves for HQand CC were obtained in the range of1×10^-6to2.3×10^-4mol L^-1with the detection limits of7.2×10^-7mol L^-1and8.2×10^-7mol L^-1respectively, when simultaneous determination of HQand CC. The proposed method has been applied to simultaneous determination of HQ and CCin water sample with simplicity and high selectivity.3. A simple “green” method for the synthesis of graphene-Pt nanocomposite film wasdeveloped by using a coelectrodeposition technique. Graphene-Pt modifed electrodes showedexcellent catalytic activity towards electrochemical oxidation of AA, DAand UAcompared tothat of pure graphene film modifed electrode. The electrochemical oxidation signals of AA,DA and UA arewell separated into three distinct peaks with peak potential separation of171mV,288mV and343mV between AA-DA, DA-UA and AA-UA respectively in CV studies. The excellent electrocatalytic behavior of graphene-Pt may lead to new applications inelectrochemical analysis.