氢化碳纳米材料的合成及其性质的研究

发布时间：2018-07-28 19:26

【摘要】：氢化碳纳米材料具有优异的机械、电学和光学等性质，广泛的应用于摩擦学、电极材料、储氢材料、超级电容和传感器等领域。已有研究表明，氢化碳纳米材料中，其形貌、结构和氢化程度等参数对其性质有决定性的影响，因此，探索简单有效的制备方法，以及实现对氢化碳纳米材料的形貌、结构和氢化程度等重要参数的调控，一直是该领域人们努力的方向，具有重要的实际意义和应用价值。基于课题组最近发展的高温高压溶剂热方法，本论文针对上述科学问题展开了研究。研究中以三氯乙烷、溴苯作为碳源，研究了不同碳源、反应温度等实验参数对制备碳纳米结构的影响。成功制备出了不同氢化程度的氢化碳纳米球（Hydrogenated Carbon Nanospheres, HCNSs）和纳米石墨结构，并对样品的光学、电化学性质进行了系统研究，得到了以下结果： 1.三氯乙烷与钾在100-150oC温度区间内反应能够生成HCNSs，HCNSs的氢化程度与反应温度有关，温度越高，氢化程度越低。HCNSs的尺寸也随温度的变化而变化，较高的反应温度下会生成较大的碳纳米球。100oC下合成的HCNSs，其平均直径为150nm，而在150oC下，HCNSs的平均直径为300nm。HCNSs具有洋葱状类石墨结构，石墨片层沿着碳球的曲面以波浪状排列；氢化导致洋葱状结构的结晶性较低，并且存在较多的缺陷。 2. HCNSs用于锂离子电池负极材料时，100oC碳球的可逆循环容量达到了820mAh g-1，是石墨理论容量(372mAh g-1)的2倍多，优于150oC碳球的450mAh g-1。两者都表现出很高的循环稳定性。HCNSs的电化学性能与其独特的形貌、结构以及氢化程度密切相关。较高的氢化程度、较小的尺寸和较低的结晶性是100oC碳球具有更优异电化学性能的主要原因。 3.碳基材料的铁磁行为是近年来的研究热点。对HCNSs的室温磁性测试表明，HCNSs在室温下表现出铁磁特征，饱和磁化强度为3*10-3emu/g，矫顽力约为100G。HCNSs的铁磁行为可能是多种因素综合的结果。波浪状排列的石墨片层所导致的负高斯曲率以及较高的缺陷浓度可能是样品磁性的主要原因。 4.利用溴苯和二溴苯在溶剂热条件下与钾反应，生成了两种分子尺寸大小不同的氢化碳纳米材料。对样品的荧光测试表明，由于分子尺寸的差异，，从而表现出不同的荧光强度。分子中含碳量较少的样品，其荧光性较强。这些实验结果为氢化碳纳米结构碳纳米结构的可控制备、性质以及形成机制提供了重要实验和理论基础，也为制备高性能的锂电池负极材料提供了一条可行途径。
[Abstract]:Hydrogenated carbon nanomaterials have excellent mechanical, electrical and optical properties, and are widely used in tribology, electrode materials, hydrogen storage materials, super capacitors and sensors. Previous studies have shown that the morphology, structure and degree of hydrogenation of hydrogenated carbon nanomaterials have a decisive effect on their properties. Therefore, simple and effective preparation methods and realization of morphology of hydrogenated carbon nanomaterials have been explored. The regulation of important parameters, such as structure and hydrogenation degree, has always been the direction of people's efforts in this field, and has important practical significance and application value. Based on the recent development of high temperature and high pressure solvothermal methods, this paper focuses on the above scientific problems. The effects of different carbon sources and reaction temperature on the preparation of carbon nanostructures were studied using trichloroethane and bromobenzene as carbon sources. The structures of hydrogenated carbon nanospheres (Hydrogenated Carbon Nanospheres, HCNSs) and graphite with different hydrogenation degrees were successfully prepared. The optical and electrochemical properties of the samples were systematically studied. The following results were obtained: 1. The hydrogenation degree of HCNSs can be related to the reaction temperature. The higher the temperature, the lower the hydrogenation degree. The size of HCNSs changes with the change of temperature. At higher reaction temperature, larger carbon nanospheres. 100oC were formed, the average diameter of HCNSs was 150nm, while the average diameter of HCNSs under 150oC was 300nm.HCNSs with an onion like graphite structure. The graphite lamellae was arranged in waves along the surface of the carbon spheres. Hydrogenation leads to lower crystallinity of onion-like structure and more defects. 2. 2. The reversible cycle capacity of the 100oC carbon sphere of HCNSs used in the cathode material of lithium ion battery is more than 2 times that of the graphite theoretical capacity (372mAh g -1), which is better than that of the 450mAh g 1 of the 150oC carbon sphere. The electrochemical properties of HCNSs are closely related to their unique morphology, structure and hydrogenation degree. Higher hydrogenation degree, smaller size and lower crystallinity are the main reasons for the better electrochemical properties of 100oC carbon spheres. Ferromagnetic behavior of carbon-based materials is a hot topic in recent years. The magnetic properties of HCNSs at room temperature show ferromagnetic characteristics. The saturation magnetization is 310-3 emu / g, and the coercivity of 100G.HCNSs is probably the result of a combination of many factors. The negative Gao Si curvature and high defect concentration caused by wavy graphite laminates may be the main reasons for the magnetic properties of the samples. 4. Two kinds of hydrogenated carbon nanomaterials with different molecular sizes were prepared by the reaction of bromobenzene and dibromobenzene with potassium under solvothermal conditions. The fluorescence measurements of the samples show different fluorescence intensity due to the difference of molecular size. The fluorescence of the sample with less carbon in the molecule is stronger. These results provide an important experimental and theoretical basis for the controllable preparation, properties and formation mechanism of hydrogenated carbon nanostructures, and also provide a feasible way for the preparation of high performance cathode materials for lithium batteries.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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