宏观尺寸碳纳米薄膜的构筑、物性及应用

发布时间：2018-11-20 19:27

【摘要】：纳米材料的宏观结构结合了纳米材料的优异物性以及宏观尺寸的良好操作性,是纳米研究及应用的重要载体。本论文从超顺排碳纳米管薄膜和石墨烯出发,研究了宏观尺寸碳纳米薄膜的构筑、物性和相关应用。利用超顺排碳纳米管网络和石墨烯之间较强的范德华力,我们实现了大面积化学气相沉积法石墨烯的干净剥离,获得了厘米尺寸、超薄、透明、导电、高力学强度的碳纳米管-石墨烯复合薄膜。由于碳纳米管网络的多孔特性,薄膜中存在大面积、准连续的悬空石墨烯。复合薄膜一面是单层石墨烯另一面是多孔碳纳米管网络的结构特点使其具有接近90%的电子透过率。基于这些特性,我们发展了复合薄膜作为真空电子器件栅极和透射电镜样品支持膜的应用。我们进一步地将这种基于范德华力的二维材料剥离及复合薄膜制备的方法进行了推广,实现了化学气相沉积法二硫化钼的有效剥离和碳纳米管-二硫化钼复合薄膜的制备。基于单层超顺排碳纳米管薄膜有序、连续的特点,我们使用超顺排碳纳米管薄膜作为碳纤维以及石墨纤维薄膜制备的模板,通过热解碳沉积以及高温热处理,实现了有序碳纤维和石墨纤维薄膜的连续制备。我们从应变能的角度对纤维石墨层的堆垛情况以及纤维的截面形状在石墨化过程中的转变进行了分析。利用制备的碳纤维和石墨纤维薄膜良好的导电性和力学强度,我们展示了其作为锂离子电池电极的应用。进一步地,我们将这种“积碳+石墨化”的方法推广到了碳纳米管线体系,实现了碳纳米管线拉伸强度和杨氏模量的显著提高。利用超顺排碳纳米管具有显著热声效应的特点,我们将超顺排碳纳米管细线薄膜集成到了带有图形化微槽的硅片上,获得了碳纳米管热声芯片。以此为基础,我们进行了热声效应的机理研究。热声理论预言了使用温度波波长表征的热效应的空间局域性。通过控制硅片上微槽的深度,以精确改变碳纳米管细线薄膜和基底的间距,我们定量研究了不同基底距离对于碳纳米管细线热致发声的影响,验证了热声效应的温度波理论,同时定量确定了温度波的波长。在此基础上,通过进一步优化设计,我们实现了碳纳米管热声耳机的制备。
[Abstract]:The macrostructure of nanomaterials combines the excellent physical properties of nanomaterials and the good maneuverability of macroscopical dimensions, so it is an important carrier for the research and application of nanomaterials. In this paper, the construction, physical properties and related applications of macroscopically sized carbon nanotube films and graphene films were studied from the point of view of supercis carbon nanotube films and graphene. Using the strong van der Waals force between the ultracis carbon nanotube network and graphene, we have realized the clean stripping of graphene by large area chemical vapor deposition, and obtained centimeter size, ultra-thin, transparent, conductive. Carbon nanotube-graphene composite film with high mechanical strength. Due to the porous properties of CNT networks, there are large areas of quasi-continuous suspended graphene in the films. The structure of porous carbon nanotube network on one side of the composite film is graphene monolayer on the other side and the electron transmittance of the composite film is nearly 90%. Based on these characteristics, we have developed the applications of composite films as gate and TEM sample support films for vacuum electronic devices. We have further extended the two dimensional material stripping and composite film preparation based on van der Waals force to realize the effective stripping of molybdenum disulfide by chemical vapor deposition and the preparation of carbon nanotube-molybdenum disulfide composite film. Based on the orderly and continuous characteristics of monolayer supercis carbon nanotubes films, we use them as templates for carbon fiber and graphite fiber films, which are prepared by pyrolytic carbon deposition and high temperature heat treatment. The continuous preparation of ordered carbon fiber and graphite fiber films has been realized. From the point of view of strain energy, the stacking of fiber-graphite layer and the transformation of fiber cross-section shape during graphitization are analyzed. With the good electrical conductivity and mechanical strength of the carbon fiber and graphite fiber films, we have demonstrated their application as electrodes for lithium ion batteries. Furthermore, we extend the method of "carbon deposition graphitization" to the carbon nanopipeline system, and achieve a significant increase in tensile strength and Young's modulus of the carbon nanopipeline. Taking advantage of the remarkable thermoacoustic effect of supercis carbon nanotubes, a thermoacoustic chip for carbon nanotubes was obtained by integrating thin wire films of carbon nanotubes onto silicon wafers with graphical microgrooves. Based on this, the mechanism of thermoacoustic effect is studied. The thermoacoustic theory predicts the spatial localization of the thermal effect represented by the temperature wave length. By controlling the depth of the microchannel on the silicon wafer and changing the distance between the thin carbon nanotube thin film and the substrate accurately, we quantitatively studied the influence of different substrate distance on the thermosyphonic sound of the carbon nanotube thin wire, and verified the temperature wave theory of thermoacoustic effect. At the same time, the wavelength of temperature wave is determined quantitatively. On this basis, through the further optimization design, we have realized the carbon nanotube thermoacoustic headset preparation.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ127.11;TB383.2

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