The Preparation And Electrochemical Application Of Graphene Based Nanomaterials

Graphene is a two-dimensional carbon nanomaterial composed of monolayers of carbon atoms arranged in a honeycombed network.Because of its excellent conductivity properties,such as well biocompatibility,large specific surface area,superior mechanicaland properties and other outstanding properties,such nanomaterial has aroused great interest in the fields of sensors,electrochemistry and materials science.However,graphene is hydrophobic and tends to form agglomerates due to the van der Waals interactions and strong π-π stacking,thus limit its applications,especialy in the field of electrochemistry.It is known that graphene-based nanocomposites can be effective in improving the graphene solubility.In addition,such nanocomposite can also exhibit synergistic effect of the composed componenents.Based on that,the performance of the as fabricated electrochemical biosensor can be greatly improved.The main research work of the thesis are summarized as follows:1.Novel functionalized graphene nanosheets,which was Poly(1-vinyl-3-butylimidazolium)bromid modified graphene(denoted as Poly(ViEtIm+Br-)-GP)was synthesized via the π-π interaction between graphene nanosheet and polymeric ionic liquids.Based on the ion-exchange property of the modified Poly(ViEtIm+Br-),AuCl4-can be further immobilized onto nanosheet.After the in-situ reduction,mono-dispersed Au nanoparticles can then be fabricated,thus made the construction of AuNPs/Poly(ViEtIm+Br)-GP nanocomposite.The morphology and structure of the functionalized graphene was characterized by TEM,UV-vis and XRD measurements.The graphene based nanocomposite was then utilized to fabricate AuNPs/Poly(ViEtIm+Br-)-GP/GC electrode.The electrochemical behavior of the modified electrode toward the reduction of hydrogen peroxide was also investigated.In addition,Glucose oxidase(GOD)was immobilized onto the AuNPs/Poly(ViEtIm+Br-)-GP modified glassy carbon(GC)electrode by electrostatic interaction.The GOD/AuNPs/Poly(ViEtIm+Br-)-GP/GC modified electrode can not only realize the direct electron transfer between the immoblized GOD and the surface of electrode,but also exhibit excellent electrocatalytic activity for glucose determination.2.Two novel water soluble carbon nanotubes/graphene composites,which were carboxylated carbon nanotubes/graphene(MWNTs-COOH/graphene)and MWNTs/sulfonated graphene(MWNTs/GP-SO3H)were synthesized via π-π self-assembly method.The carbonous nanocomposites were characterized by TEM、SEM、FT-IR、UV-Vis and Zeta potential measurements.Moreover,the electrochemical behavior of MWNTs-COOH/graphene/GC and MWNTs/GP-S03H/GC modified electrodes were also investigated.For example,the MWNTs-COOH/graphene/GC modified electrode was applied for the selective determination of dopamine.The MWNTs/GP-SO3H/GC electrode also exhibited excellent catalytic performance for the detection of hydrogen peroxide with a wide linear range from 0.5 to 7 mM.