Preparation And Performance Of Graphene Composite Based On Layer-by-layer Technique

Nowadays, more and more attention has been paid to graphene. As its special structureand excellent performance such as electricity, thermology, mechanics and so on, graphene hasbecome one hot spot since it was found in2004. Particularly, graphene-based composites, as anew kind of hybrid materials, have aroused much interest due to their synergistic and novelproperties via the combination with different materials. In recent years, layer-by-layerself-assembly technique(LbL-SA) has attracted much attention because of the characteristicssuch as simple facilities, easy to control, various film-forming component and so on. Duringthe past decade, it is widely used as a powerful and versatile method for the preparation ofultrathin films. In this paper, several novel kinds of graphene composites are prepared viaLBL-SAtechnology.And the main contents can be divided into the following three parts：1. The preparation of PAA-g-GR/PANI hybrid films.Using negatively charged PAA-g-GR and positively charged PANI as two buildingblocks, a new PAA-g-GR/PANI hybrid film is prepared. The multilayer films forming processwere investigated by fourier transform infrared spectroscopy(FTIR), ultraviolet-visibleabsorption spectrum(UV-vis). The results showed that a gradual increase intensity of theUV-vis absorbance spectra with the characteristic absorbance of each component is observed,which indicated a continuous growth of the bilayer system and confirmed the successful LBLassembly of PAA-g-GR with PANI. The surface morphology of {PAA-g-GR/PANI}nmultilayer film was observed by field emission scanning electron microscopy(FE-SEM),which give further evidence for consecutive growth of the multilayer. The electrochemicalproperty of the hybrid films is investigated which showed electroactivity in a wide range ofpH. In addition, the PAA-g-GR/PANI hybrid film exhibited good electrocatalytic abilitytoward H2O2. The linear response range is0.005~0.3mmol/L and the detection limit is1×10-5mol/L.2. Preparation, characterization and application of graphene/hemoglobin composite film.Using positively charged hemoglobin(Hb) and negatively charged polyacrylic acid(PAA)stabilized graphene(PAA-g-GR) as building blocks, a uniform {PAA-g-GR/Hb}nmultilayerfilm was prepared based on layer-by-layer(LBL) self-assembly technology. The PAA wasused not only to disperse and stabilize graphene sheets in aqueous solution, but also facilitatethe growth of the PAA-g-GR/Hb multilayer films via electrostatic interactions betweenPAA-g-GR and Hb. The electrocatalytic response of {PAA-g-GR/Hb}nmultilayer filmmodified glassy carbon electrode toward hydrogen dioxide(H2O2) is investigated by cyclicvoltammetry(CV) and chronoamperometry(CA). The results showed that the{PAA-g-GR/Hb}nfilm modified electrode exhibited a wide linear response range of1×10-6~1×10-4mol/L with a correlation coefficient of0.999for the detection of H2O2. And theresponse time and detection limit (S/N=3) was determined to be5s and8×10-7mol/L,respectively. Another attractive feature was that the {PAA-g-GR/Hb}nmultilayer filmmodified electrode was highly stable, and could be used for a long time. Furthermore, the{PAA-g-GR/Hb}nfilm modified electrode exhibited good selectivity for H2O2and the interferences from the oxidation of common interfering species(NO3-, SO42-, Cl-, ascorbic acid,dopamine and acetic acid) are avoided. Therefore, such LBL self-assembly technology hasgood application potential to fabricate many other kinds of composites for biosensors.3. The preparation of GR/biological macromolecules composite film.Hyaluronic acid(HA), dopamine(DOPA), chitosan,3-hydroxyphenylaceticacid(3,4-diHPP) have good biocompatibility. In this experiment, HA-DOPA and3,4-diHPP-chitosan are synthesized by amide bond reaction in each group. Then, HA-DOPAand3,4-diHPP-chitosan are modified to the surface of graphene to form HA-DOPA-GR and3,4-diHPP-chitosan-GR. Using positively charged3,4-diHPP-chitosan-GR and negativelycharged HA-DOPA-GR as building blocks,{HA-DOPA-GR/3,4-diHPP-chitosan-GR}nmultilayer film was prepared based on layer-by-layer (LBL) self-assembly technique. Fouriertransform infrared spectroscopy(FTIR), X-ray diffraction(XRD), Raman shift(Raman),thermal gravimetric analysis(TGA), Zeta potential are used to represent the structure of thebuilding blocks; UV-visible absorption spectrum(UV-vis), cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS) demonstrate the LBL-SA progress. What’smore, the biological activity of horseradish peroxidase was kept well when it wasimmobilized to {HA-DOPA-GR/3,4-diHPP-chitosan-GR}3multilayer film, and it showedsensitive response to H2O2.