Construction Of Modified Electrode Based On Carbon Nanotubes And Graphene And Its Application In Analysis

Carbon nanotubes and graphene with many unique properties such as high surface area, high electrical conductivity have been used as excellent electrochemical sensing material. In recent years, electrochemical sensors based on carbon nanotubes and graphene composites have aroused the wide attention of all. The new type of composite film modified electrode become hot topics in the study of electroanalytical chemistry using carbon nanotubes and graphene as the added phase combining with the other electrode materials such as metal nanoparticles, polymer, surface active agent. In this thesis, the electrochemical sensor based on carbon nanotube or graphene and metal nanocomposite was built by connecting carbon nanotubes or graphene with gold nanoparticles, quantum dots surface and active agent through the way of electrical aggregation, non covalent bond. And through the analysis of application in the actual samples, electrochemical sensing properties of the nano composites were discussed. The results obtained had a beneficial enlightening and guiding role for constraction of modified electrode based on the nanocomposite of carbon nanotubes or graphene.1. Simultaneous determination of dihydroxybenzene isomers at ZnSe QDs/MWNTs-Nafion composite film modified glassy carbon electrodeIn this section, the ZnSe QDs/MWNTs-Nafion electrochemical sensing system was fabricated using the non covalent bond between glutathione which was used as modifier of ZnSe QDs and functionalized MWNTs. The nano composites and the interface of electrochemical sensing were characterized by TEM and EIS. The electrochemical sensing system showed excellent electrochemical catalytic activities and high selectivity towards the oxidation of catechol (CC), resorcinol (RC) and hydroquinone (HQ). Under the optimized experimental conditions, the three isomers can be determined simultaneously and sensitively. The anodic peak current were linear over ranges from2.0×10-6to5.0×10-4mol/L for CC, from1.4×10-5to1.0×10-4mol/L for RC, from2.0×10-6to1.0×10-3mol/L for HQ, with the detection limits of2.0×10-8mol/L,2.0×10-6mol/L and2.0×10-8mol/L, respectively. A new method for determination of CC, RC and HQ in the real samples was established.2. Determination of resorcinol based on GNP/L-cys/MWNTs-Nafion composite film modified glassy carbon electrodeIn this section, by using the coordination between GNP and L-cys,the non covalent bond between L-cys and MWNTs, through the methods of dropping and electric aggregation, the three-component composite film of GNP/L-cys/MWNTs-Nafion was fabricated. The nano composites and the interface of electrochemical sensing were characterized by SEM and EIS. The modified electrode showed excellent electrochemical catalytic activities towards the oxidation of RC, improved the sensitivity of determination RC. The calibration curve for RC was obtained in the range of4.0×10-7～8.0×10-5mol/L with a low detection limit of2.0x10-7mol/L (S/N=3). A new method for determination of RC in the real samples was established.3. High sensitive determination of theophylline based on GNP/L-cys/Gr-Nafion composite film modified glassy carbon electrodeIn this section, by using the coordination between GNP and L-cys, with large specific surface area and superior electron conduction of Gr, through the methods of dropping-electric aggregation-electrostatic adsorption, three-component composite film of GNP/L-cys/Gr-Nafion was fabricated. This composite film was characterized by TEM and SEM. The modified electrode showed excellent electrochemical catalytic activities and high sensitivity towards the oxidation of theophylline (TP). The peak current of TP was proportional to its concentration at the range of4.0x10"9to6.0×10-5mol/L with a detection limit4.0×10-10mol/L (S/N=3). The method for determination of TP have higher sensitivity han other electrochemical methods have been reported. At the same time, the proposed method for the simultaneously determination of TP and caffeine (CF) was also investigated. A new high sensitive method for determination of TP and CF in the tablet and tea was established.4. High sensitive determination of2,4-DichIorophenol based on CTAB/PSS-Gr/ Nafion composite film modified glassy carbon electrodeIn this section, negatively charged PSS-Gr(Poly(sodium-p-styrenesulfonate) functionalized graphene) was synthesized and characterized by infrared spectrometry(IR) and ultraviolet and visible spectrophotometry(UV-Vis). The CTAB/PSS-Gr/Nafion/GCE modified electrode was fabricated using the electrostatic interaction between cetyltrimethylammonium bromide (CTAB) and PSS-Gr. The modified electrode showed excellent electrochemical catalytic activities, high sensitivity and high selectivity towards the oxidation of2,4-Dichlorophenol(2,4-DCP). The peak current of2,4-DCP was proportional to its concentration at the range of2.0×10-8to4.0×10-6mol/L with a detection limit2.0×10-9mol/L(S/N=3). A new method for determination of2,4-DCP was established.