| Carbon nanotubes (CNTs) are arrangements of carbon hexagons that are formed into tiny tubes. They usually have a diameter ranging from a few angstrom to tens of nanometers and can have lengths up to several micrometers. There are two distinct types of carbon nanotubes. The so-called single-walled carbon nanotube (i.e., SWNT or graphene tube) is made of one layer of graphene sheet while the multi-walled carbon nanotube (i.e., MWNT or graphitic tube) consists of more than one layer. Since their discovery bv lijima, CNTs have attracted much attention and opened up a new era in material science and nanotechnology due to their fascinating and extraordinary structural, mechanical, electrical, and electrochemical properties as well as their promise in the field of materials science. Now, CNTs have been widely used in various fields such as physics, chemistry, energy and material science.Everything has two sides, and there is no exception for carbon nanotubes. CNTs possess many attractive advantages, but the insolubility of CNTs in almost all solvents limits their application in the fabrication of CNTs-based electrochemical sensor. It is very interesting and full of challenge to fabricate CNTs-based electrochemical sensor (or CNTs-modified electrodes) for electrochemical researchers since the subtle electronic properties suggest that CNTs have the ability to promote electron transfer.In this thesis, carbon nanotubes were successfully dispersed into ethanol and water by utilizing special technology, which expanded the application areas of CNTs. Based on this, some kinds of CNTs-film-modified electrodes have been fabricated. Then, their applications in electroanalysis have been studied with great details. The main researches were summarized as follows:Section one: Study on the MWNT-Nafion composite film-modified electrodeIn the presence of Nafion, an excellent cation-exchange polymer, multi-wall carbon nanotube (MWNT) was easily and homogeneouslyIVdispersed into ethanol. Consequently, a uniform MWNT-Nafion film was obtained on a glassy carbon electrode (GCE) surface via solvent evaporation, and then characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transfer (FT) IR spectra and electrochemical methods. The electrochemical behaviors of dopamine (DA) were examined. In comparison with the bare GCE and the Nafion-modified GCE, the MWNT-Nafion film-modified GCE shows obvious electrocatalytic activity to DA since it not only enhances the peak current but also lowers the overpotential. Moreover, the MWNT-Nafion film exhibits excellent selectivity towards DA even in the presence of high concentration of ascorbic acid (AA) and uric acid (UA).Section two: Studies on the MWNT-dihexadecyl hydrogen phosphate (DHP) film-modified electrodeSurfactant contains hydrophobic group and hydrophilic group, and has been extensively used in electrochemistry. In the presence of dihexadecyl hydrogen phosphate (DHP), which contains two long C-H chains, MWNT was successfully dispersed into water. The resulting MWNT-DHP dispersion is very stable and homogeneous. Through evaporating solvent, a uniform and stable MWNT-DHP film was obtained on the electrode surface.(1) The MWNT-DHP thin film on the electrode surface was characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and some electrochemical techniques such as electrochemical impedance spectra (EIS) and cyclic voltammetry (CV).(2) Utilizing the subtle properties of MWNT (hollow structure, closed topology, strong adsorptive ability and huge specific surface area) and the induced adsorption behavior of I", a sensitive electrochemical technique for the simultaneous determination of Cd2+ and Pb2+ has been developed. This sensing and determining system possesses following advantages: free of mercury, low detection limit, fast response, low cost and excellent reproducibility. Moreover, this proposed method was successfully used to detect Cd2+ and Pb2+ in...
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