Research Of Electrochemical Sensors Based On Carbon Nanotubes/Graphene Composites

Carbon nanomaterials have been widely used in the fabrication and research of the electrochemical sensors because of their excellent mechanical,electrical and chemical properties.Graphene and carbon nanotubes are nanometer-sized carbon materials with the excellent properties,but they have some unique properties due to their different structures.In order to combine the advantages,the carbon nanotubes/graphene composites were fabricated,and the composites exhibited more excellent properties than any single material by the synergetic effect.With the further study of carbon nanocomposites,the promising application prospects are also revealed.In this study,two electrochemical sensors based on carbon nanotubes/graphene composites were prepared by different modification methods,which were used for the simultaneous detection of three dihydroxybenzene isomers and the simultaneous detection of four kinds of DNA bases,respectively.The main contents are as follows:1.Based on the covalent self-assembly of aminated reduced graphene oxide(rGO-NH2)and carboxylated multi-wall carbon nanotubes(MWCNTs-COOH),highly stable MWCNTs/rGO composite film was fabricated on glassy carbon electrode(GCE)surface.MWCNTs/rGO modified electrode was obtained.The MWCNTs/rGO modified GCE was found to be a highly sensitive electrochemical sensor for the simultaneous determination of hydroquinone(HQ),catechol(CC)and resorcinol(RS).Scanning electron microscopy(SEM),electrochemical impedance spectroscopy(EIS),cyclic voltammetry(CV)and differential pulse voltammetry(DPV)were used to characterize the sensor.The results showed that the modified electrode had obvious electrocatalytic effect on the oxidation of three dihydroxybenzene isomers and the better peak separation and the larger peak current response of the three isomers were obtained at the modified electrode.Moreover.the MWCNTs/rGO/GCE showed good stability,reproducibility and selectivity.Finally,This electrochemical sensor could be used to detect the actual sample.2.Highly stable and controllable graphene(GR)and multi-walled carbon nanotubes(MWCNTs)composite modified electrode was fabricated by the electrostatic self-assembly method combined with photocrosslinking technique.In the assembling process,diazoresin(DAR)serviced as an arm linker between carboxylated GR and MWCNTs,and UV irradiation converted the electrostatic interaction among layers into covalent bonds.The fabrication process was monitored by UV-vis spectra,The composite films were extensively characterized by UV-Vis spectroscopy,scanning electron microscopy and electrochemical impedance spectroscopy.Electrochemical studies indicated that the MWCNTs/GR composite film modified electrode offered an excellent strategy for the simultaneous determination of all four DNA bases(adenine,thymine,guanine and cytosine).Under the optimum conditions,the(MWCNTs/GR)2/GCE exhibited low detection limit,good stability and reproducibility for determination of four bases.Moreover,the modified electrode was successfully applied to the detection of DNA bases in salmon sperm DNA sample with satisfactory results.