Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

The Functionalization of Carbon Nanotube with Poly-(4-Vinylpyridine) and Its Appli-Cation in Electrochemistry

Author LiNa
Tutor YuanJunHua
School Zhejiang Normal University
Course Analytical Chemistry
Keywords CNTs functionalization electrochemistry application
Type Master's thesis
Year 2012
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Since they were discovered in1991by Iijima, Carbon nanotubes (CNTs) have attracted great interests in most fields due to their peculiar structural, unique physical and chemical properties. Their excellent characteristics included anisotropic, high mechanical strength and flexibility, good thermal and electrical conductivity, large specific surface area, etc. Their application were very extensive because of these fine performance. The major areas of CNTs’s research were field emission devices, hydrogen storage material, lithium ion battery, electrochemical capacitor, super composites and devices including biosensors, drug and vaccine delivery vehicles, etc. So it was very comprehensive in the application of electrochemistry, However there was a major problem in the application, it was difficult for carbon nanotubes in almost all sorts of solvents to disperse, especially in the biological system, this largely restricted the application study of CNTs. In order to improve their dispersibility, especially in the aqueous solution, we needed to modify carbon nanotubes. Different strategies for the functionalization of CNTs have been proposed, such as non-covalent and covalent functionalization, the covalent functionalization method mainly included port functionalization and lateral wall functionalization; the non-covalent functionalization method mainly included polymer functionlization, starch functionlization, dye molecules functionalization, cyclodextrin functionalization and ionic liquids functionalization, etc. The modified carbon nanotubes not only kept the original specific properties but also showed the activity of the modified groups in the reaction, it was helpful to the dispersion and assembling of carbon nanotubes, as well as its surface reaction. In this text, we choosed poly-(4-vinylpyridine)(P4VP) to functionalize carbon nanotubes and synthetized the Prussian blue analogues sensors later; At the same time we functionalized carbon nanotubes using the ionic liquids and prepared the manganese dioxide deposited on the carbon nanotubes. finally, We studied their application in electrochemistry through the experiments.According to the report, I focused on the following three parts of the work:(1) Poly-(4-vinylpyridine)(P4VP) was grafted to multiwalled carbon nanotubes (MWCNTs) by an in situ polymerization. This grafted polymer played two roles in the synthesis of Prussian Blue (PB)/MWCNTs composites:1. a stabilizer to protect PB nanoparticles from aggregation;2. a linker to anchor these nanoparticles on the surface of MWCNTs. The size of PB nanoparticles deposited on MWCNTs could be controlled by in site layer-by-layer coordination of Fe3+and [Fe(CN)6]4-ions in aqueous solution. The as-prepared PB/P4VP-g-MWCNTs composites were characterized by Fourier transform infrared spectroscopy, Transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray powder diffraction, which revealed that these PB nanoparticles were uniformly distributed on the surface of MWCNTs, and grew upon layer-by-layer assembly. A potential use of PB/P4VP-g-MWCNTs composites was demonstrated as an electrocatalysist used in the electrochemical detection of L-cysteine. The as-prepared electrodes modified with PB/P4VP-g-MWCNTs composites showed two reversible redox waves assigned to a fast surface-controlled processes. The analytical performance for L-cysteine detection was associated with the load of PB nanoparticles onto MWCNTs. In an optimal experiment, for these as-prepared electrodes, their detection limit of L-cysteine could be measured as low as0.01μM with a sensitivity778.34nA·μM-1·cm-2.(2) NiHCFs nanoparticles are deposited onto the surface of multiwalled carbon nanotubes (MWCNTs) with a grafted poly(4-vinylpyridine). The as-prepared NiHCF/P4VP-g-MWCNTs composites are characterized by transition electron microscope (TEM) and fourier transform infrared spectroscopy (FTIR), which confirms the presence of NiHCFs nanoparticles, and shows that NiHCFs nanoparticles are highly dispersed on the surface of MWCNTs in high density. Cyclic voltammograms (CVs) exhibit a great enhancement for NiHCFs/P4VP-g-MWCNTs composites in capacity and stability as ion exchanger by comparison with bulk NiHCF. The capacity for the electrodes modified with NiHCFs/P4VP-g-MWCNTs composites is69.24mC/cm-2·mg, after100cycles potential sweeping, these composites modified electrode retains its98.5%ion-exchange capacity. These composites also exhibit a higher selectivity of for Cs+over Na+ions in high concentration of Na+ion, which is confirmed by X-ray photoelectron spectroscopy (XPS).(3) Because of the rapid development of modern society and economy, there brought a lot of problems to the ecological environment and energy. People also were beginning to turn to explore the new energy which was low-carbon, clean and renewable. With the fast development of the contemporary social electrical equipment, super capacitor was chosen as a storage components of the new energy, the electrode materials was an important factor to the capacitance and performance of the super capacitor. Because manganese had many advantages, such as the abundant natural resources, non-toxic, to be good to environment, structure diversification and so on, these made the manganese oxide was widely used in energy, environment, catalytic, adsorption, ion exchange, communication and so on. In this text, combing with carbon nanotubes and manganese dioxide advantages, we choosed the brominationl-cetyl-3-methyl imidazole to functionalize MWCNTs and synthetized the MWCNTs-MnO2capacitor materials, at the same time, we carried out the characterization of scanning electron microscopy (SEM), the Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy (XPS) to them to study the morphology and the application in electrochemistry of the prepared complex.

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