Study On The Synthesis Of Electrode Materials Based On Novel Conducting Polymer-Graphene And Their Electrochemical Properties

Recently, the application of novel modified electrodes with high electrocatalytic and electrochemical performance have been achieved with the developmemt of various carbon materials. Graphene shows great prospect in new energy, sensing devices and many other fields due to its great surface area and excellent electrical properties. This thesis aimed at developing novel graphene and conducting polymer-based composites as electrode materials, which concentrated on the controllable synthesis of the multi-component composite electrodes by various preparation approaches. The morphologies of polymers grown on the graphene substrate were investigated; and the electrochemical properties of the composites were studied. The main contents were as follows:1) An efficient and eco-friendly microwave-assistant method was developed to synthesize a ternary composite of polypyrrole-hemin-reduced graphene oxide (PPY-He-RGO). The polymerization of pyrrole monomer and the reduction of graphene oxide adsorbing hemin were performed simutaneously in isopropanol/water mixed mediums by microwave heating, without using an extra reducing or oxidizing agents. Shuttle-like polypyrrole (PPY) nanoparticles were decorated on He-RGO sheets. Such a composite could fully unitlize the synergistic effect and multifunction of each component. The stability of hemin molecules could be enhanced by immobilizing on the sheets. The good conductivity of RGO and PPY with well-controlled nanostructure provided a highly conductive network in the ternary composite, which promoted the electron transfer among hemin, analytes and electrode. Meanwhile, it retained electrocatalytic activity for H2O2. Acting as a third-generation mediator and mimic enzyme, the PPY-He-RGO exhibited high electrocatalytic activity towards the reduction of H2O2 with a low detection limit of 0.13 μM. The microwave heating method also provides an opportunity to large-scale production of other nanocomposite.2) Two kinds of modified glass carbon electrodes (EPolymer-He-RGO/GCE and He-RGO-EPEDOT/GCE) were composed of hemin-RGO and conducting polymers by different fabrication routes. The conducting PPY and poly (3,4-ethylene dioxythiophone) (PEDOT) were prepared by electrochemical polymerization. The combination of conducting polymers with hemin could facilite the electrochemical response to H2O2. The results from cycling voltammetry (CV) and differential pulse boltammetry (DPV) showed that both EPolymer-He-RGO/GCEs exhibited good electrocatalytic activities for the reduction of H2O2 and good stability, while EPPY-He-RGO/GCE was better than EPEDOT-He-RGO/GCE. For the simultaneous determination of hytdroquinone (HQ) and catechol (CT), it was found that, He-RGO-EPEDOT/GCE possessed the higher catalytic activity and response current with comparison to EPEDOT-He-RGO/GCE. The quantitative determination of HQ was performed at a He-RGO-EPEDOT/GCE by DPV. A detection limit of 1.2 μM was obtained.3) Series graphene oxdie (GO) composites with polyaniline (PANI), GO-PANI (GOP), were synthesized by in-situ polymerization. The effects of the feeding ratio and acidic dopants were investigated on the morphologies and electrochemical properties of the composites. The results showed that the as-prepared hybrid materials of GOP possessed double-layer capacitance and pseudocapacitance. The GOP composites obtained in the isopropanol/water mediums showed high conductive and electrochemical performance, due to the presense of PANI nanoparticles on the surface of GO and PANI fibers interconnecting the sheets. When camphorsulfonic acid (CAS) was used as a dopant, a very thin film of PANI, with large particles and short and thick fibers, grown and coated on the GOP surface.4) A ternary composite (GO-PANI-PMA, GOPM) with GO and copolymer PANI-poly (metanilic acid) (PMA) was in-situ copolymerized. The unique particles of copolymer were coated on the RGO surface without agglomeration. The successful copolymerization between PANI and PMA was confirmed by FTIR. The electrochemical results indicated that the ternary composite of GOPM exhibited better electrochemical activity and stability in neutral mediums, compared to the binary composite of GOP. The GOPM composite modified electrodes showed good electrocatalytic activity towards ascorbic acid (AA) and 4-acetamidophenol (AP). The obtained GOPM composite has a promising trend to expand the application of polyaniline derivatives in sensor field.