碳纳米管场发射性能的实验研究

发布时间：2018-04-20 13:03

本文选题：碳纳米管 + 场发射　；参考：《浙江大学》2015年博士论文

【摘要】：碳纳米管是一维空心管状的碳纳米材料,长径比大,功函数低,具有优异的电学、热学和力学性能,是很理想的场发射负极材料。本文研究了采用不同结构的碳纳米材料和不同结构形式电极的场发射性能,主要包括以下三个方面：首先是碳纳米管基于导电玻璃衬底的场发射性能,其次研究了不同衬底对碳纳米管场发射性能的影响,第三是石墨烯等sp2杂化碳纳米材料掺杂的碳纳米管场发射性能。第一章绪论部分,主要介绍了碳纳米材料家族的分类和结构特点,重点对碳纳米管的结构、性质、应用和常用的表征方法进行阐述。然后介绍了场发射的理论知识以及碳纳米管的场发射研究现状。第二章研究了碳纳米管基于玻璃衬底的场发射性能,特别是单壁碳纳米管的制备及其场发射。用乙醇催化的化学气相沉积法(chemical vapor deposition, CVD)制备单壁碳纳米管,研究氢气流量、催化剂和乙醇体积对单壁碳纳米管生长的影响,并测试用不同氢气流量和催化剂生长的碳纳米管薄膜的场发射性能；用丝网印刷法比较电弧放电法制备单壁碳纳米管和多壁碳纳米管的场发射性能,比较其不同的结构对场发射性能的影响。第三章主要研究了衬底对场发射性能的影响。比较了不同直径和长度的碳纳米管在泡沫镍衬底上的场发射性能,发现直径小长度短的碳纳米管场发射性能更佳。讨论了导电玻璃、镍箔和泡沫镍三种衬底基于丝网印刷法制备的碳纳米管负极的场发射性能,研究发现泡沫镍衬底对场发射性能有提高作用；最后建立了一个模型,对泡沫镍衬底改善场发射性能的原因进行了分析,其原因归结为泡沫镍的导电性和散热性更好,多孔结构有利于附着更多的碳纳米管并且能与碳纳米管构成多级结构,有效提高场增强因子。第四章研究了sp2类型碳纳米材料掺杂对碳纳米管的场发射性能的影响。首先用液相法和直接混合法制备了两种CNT/graphene复合材料,研究制备方法对场发射性能的影响,结果表明液相法制备的复合材料由于碳纳米管与石墨烯构成的导电网络更牢固而具有更佳的场发射性能。然后还对碳纳米管掺杂石墨烯的场发射性能的机理进行了模型分析,原因主要归结为掺入石墨烯后都有利于的导电性的提高,特别是增强了碳纳米管与衬底的接触；减小了碳纳米管负极薄膜的屏蔽效应；三种材料与碳纳米管构成多级结构提高了场增强因子。其次制备了三种比例的CNT/graphene,优化参数,研究石墨烯掺杂比例对场发射性能的影响。此外还制备了CNT/graphite和CNT/r-graO(reduced graphite oxide)两种复合材料,实验结果表明这两种材料掺杂也能提高碳纳米管的场发射性能。第五章对本文的内容做了简单总结,包括研究内容和主要结论,然后对当前工作做了展望,阐述了下一步可进行的研究。
[Abstract]:Carbon nanotubes are one dimensional hollow tubular carbon nanomaterials with large length to diameter ratio, low work function, excellent electrical, thermal and mechanical properties. It is an ideal field emission negative material. In this paper, the field emission properties of carbon nanomaterials with different structures and different structural forms are studied in this paper, mainly including the following three aspects: first, Carbon nanotubes are based on the field emission properties of conductive glass substrates. Secondly, the effects of different substrates on the field emission properties of carbon nanotubes are studied. Third, the field emission properties of carbon nanotubes doped with graphene and other SP2 hybrid carbon nanomaterials. In Chapter 1, the classification and structure characteristics of carbon nanomaterials are mainly introduced, focusing on carbon. The structure, properties, applications and common characterization methods of nanotube are described. Then the theoretical knowledge of field emission and the current status of Field Emission Research on carbon nanotubes are introduced. The second chapter studies the field emission properties of carbon nanotubes based on glass substrates, especially the preparation and field emission of single walled carbon nanotubes. The chemical gas catalyzed by ethanol is used. Single wall carbon nanotube was prepared by chemical vapor deposition (CVD). The effect of hydrogen flow, catalyst and ethanol volume on the growth of single wall carbon nanotubes was studied. The field emission properties of carbon nanotube films with different hydrogen flow and catalyst growth were tested. The single wall carbon nanotube was prepared by wire mesh printing method to compare the single wall carbon nanotube with the wire mesh method. The field emission properties of tube and multi wall carbon nanotube are compared. The effect of different structures on field emission is compared. In the third chapter, the effect of substrate on field emission is mainly studied. The field emission performance of carbon nanotubes with different diameter and length on the foam nickel substrate is compared. It is found that the field emission performance of small diameter and short carbon nanotubes is better. The field emission performance of carbon nanotube negative electrode prepared on three substrates of conductive glass, nickel foil and nickel foam based on screen printing is discussed. It is found that the foamed nickel substrate can improve the field emission performance. Finally, a model is established to improve the field emission performance of the foamed nickel substrate, which is attributed to foam. The conductivity and heat dissipation of nickel are better. The porous structure is beneficial to attaching more carbon nanotubes and can make up a multistage structure with carbon nanotubes and effectively improve the field enhancement factor. The fourth chapter studies the effect of SP2 type carbon nanomaterial doping on the field emission properties of carbon nanotubes. First, two kinds of CNT/ are prepared by liquid phase method and direct mixing method. Graphene composites are used to study the effect of the preparation methods on the field emission properties. The results show that the composite materials prepared by liquid phase method are more solid and have better field emission properties due to the conductive network composed of carbon nanotubes and graphene. Then the mechanism of the field emission properties of carbon nanotubes doped graphene is analyzed, and the reasons are also analyzed. It is mainly attributed to the improvement of conductivity, especially the increase of the contact between the carbon nanotube and the substrate, and the reduction of the shielding effect of the carbon nanotube negative electrode. The three materials and the carbon nanotube constitute a multistage structure to improve the field enhancement factor. Secondly, three kinds of proportions of CNT/graphene are prepared and the parameters are optimized. The effect of the proportion of graphene on the field emission is investigated. In addition, two kinds of CNT/graphite and CNT/r-graO (reduced graphite oxide) composites have been prepared. The experimental results show that the doping of these two materials can also improve the field emission properties of the carbon nanotubes. The fifth chapter makes a brief summary of the content of this paper, including the content and the main conclusions. Then, the future work is prospected, and the next step is discussed.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：O613.71;TB383.1

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