Growth of Aligned Carbon Nanotubes at Low Pressure and Their Applications
|School||East China Normal University|
|Keywords||Aligned Carbon Nanotube Array Chemical vapor deposition Low pressure High temperature pyrolysis Modified electrode Electrocatalytic oxidation|
In 1991, Japanese scientists Iijima vacuum arc evaporation of graphite electrodes, its product by high-resolution transmission electron microscopy study found that the nano-sized carbon multilayer tubes, namely multi-walled carbon nanotubes (MWNTs). The discovery immediately physical sector, chemical industry and materials science community and high-tech industrial sector, set off again after following the C 60 Research climax in the scientific community. Because of its small size, high mechanical strength, large specific surface area, high conductivity, interfacial effects, has been widely used in flat panel displays, one-dimensional quantum wires, sensors, supercapacitors, and hydrogen storage materials. Nanotubes unique atomic structure makes it exhibits a metal or semiconductor characteristics, the use of this unique electronic properties, the electrode can be made of carbon nanotubes. The surface effect of the carbon nanotubes, i.e. small diameter, high surface energy, atomic ligand insufficient, so that the high activity of the surface atoms, electron transfer occurs easily with other substances in the surrounding, electrocatalytic and electric field of analytical chemistry has broad application prospects. Directed upright carbon nanotubes (ACNT) is one of the carbon tube orientation morphology, growth density, good separation between than the haphazard arrangement and sintered together carbon tubes more easily dispersed and applications. Quartz glass substrate, depending on the preparation, the directional growth of carbon nanotubes can be divided into the template method and self-organized growth method, template method generally porous materials such as alumina, through template restrictive, so that carbon nanotubes can only Growth in accordance with a certain direction. Self-organization for directional growth method orientation growth by controlling the distribution of the catalyst on the substrate, thereby obtaining the self-organization of the carbon nanotubes, the method is simple and can be mass produced, etc., is currently the hotspot for preparing aligned carbon nanotubes, and how to obtain a Ordering consistent and controllable length and diameter, high-quality carbon nanotubes is the key issue in the preparation and application of directional arrays of carbon nanotubes. This thesis iron phthalocyanine starting material was prepared, using the pyrolysis can provide both a carbon source and a catalyst, under low pressure conditions, the use of chemical vapor deposition method on a quartz substrate was successfully prepared quality upright nanotubes, effectively reduces experimental costs, improve utilization of raw materials and the purity of the carbon nanotubes, and take advantage of its unique nature, the design of such a large area aligned CNT arrays used in electrochemical biosensors for actual samples kinds of rapid, sensitive, and accurate detection methods. The thesis is divided into three chapters: the first chapter first introduces the structure and properties of carbon nanotubes, as well as the unique nature of the aligned CNT arrays. Followed by the preparation method and the growth mechanism of aligned CNT arrays, focuses on the classification and mechanism of carbon nanotubes prepared by chemical vapor deposition. Finally, the application of carbon nanotubes in sensors, electrode materials, as well as field emission display pieces. The pyrolysis of iron phthalocyanine phthalocyanine under Chapter II low-pressure pyrolysis prepared aligned CNT arrays chapter describes the low-pressure conditions at 750 ~ 1000 ℃, quartz glass substrate, the preparation of large area highly directional carbon nano tube method. The average length of the carbon nanotubes prepared 20μm, diameter 40 ~ 70nm, bamboo-like structure of multi-walled carbon nanotubes. Experimental study of the different preparation parameters, as well as different base growth of aligned carbon nanotubes, and the growth mechanism was discussed. Field emission test, the carbon nanotubes have found the voltage of only 0.67 V · μm -1 sup> (I = 1μA), the threshold voltage of 2.5V · μm -1 sup >, has a good field emission properties. Chapter thionine / directional vertical carbon nanotube modified electrode electrochemical catalytic oxidation method for the determination of nitrite chapter describes thionine modified aligned CNT microelectrode prepared nitrite in the acidic buffer solution Electrochemical oxidation behavior. Nitrite oxidation, this electrode showed good electrochemical catalytic properties. Thionine a certain mechanism of carbon nanotube modified electrode electrochemical catalytic oxidation of nitrite. Measured by differential pulse voltammetry (DPV) oxidation peak current and the concentration of sodium nitrite in 3.0 × 10 -6 sup> 5.0 × 10 -4 sup> M range shown good linear relationship, a detection limit of 1.12 × 10 -6 sup> M. This modified electrode for the determination of nitrite in the actual sample, the results are satisfactory.