三维多孔石墨烯纳米复合材料的制备与性能表征

发布时间：2018-03-17 18:01

本文选题：三维石墨烯纳米复合材料　切入点：氧化石墨烯　出处：《河北大学》2015年硕士论文　论文类型：学位论文

【摘要】：石墨烯是一种通过碳原子sp2杂化形成的六边形蜂窝状结构二维原子晶体,其特殊的二维结构,致使其在导电性,导热性等诸多方面具有非常优异的性能。但是,二维材料在一定程度上限制了石墨烯在应用方面的拓展。石墨烯与溶剂间的作用比较弱,且二维的强共轭结构使层与层之间的范德华力很强,形成间距为0.34 nm的结合体,所以石墨烯很容易堆积却难以剥离分散,这对石墨烯功能材料的进一步加工制备和应用带来了很大的困难。采用化学氧化石墨粉制备的氧化石墨烯,不仅容易分散在多种溶剂里,还可以通过还原转化为石墨烯,因此是迄今为止研究最广泛的石墨烯衍生物。与石墨类似,氧化石墨同样保持着层状结构,不同的是,石墨片层经强酸性以及强氧化性的溶剂氧化后,引入了许多不同的含氧官能团,如羟基、环氧基、羰基和羧基等,经过剥离得到的单片层的结构,即氧化石墨烯。而且因为层状结构易于分散到溶剂中,孔结构得到了很好的保护。利用氧化石墨烯的独特性质,将二维材料组装为三维石墨烯纳米复合材料,可以很好的解决二维材料在应用上的困难,对于石墨烯的基础和应用研究具有重大意义。因此本文主要针对其含氧官能团和孔结构等特性,研究了多种三维多孔石墨烯纳米复合材料。本文的内容和成果如下:1.以氧化石墨烯为主要原料,利用氧化石墨烯层间的含氧官能团与不同硼酸衍生物反应,成功制备了三种不同的插层结构,即氧化石墨烯骨架结构材料(GOFs),并对对羧基苯硼酸做连接剂的GOF进行了锂掺杂。利用扫描电子显微镜(SEM),X射线衍射(XRD),氮气吸附测试以及热重分析(TGA)等手段对材料的不同结钩进行了分析,并采用电化学分析的方法分析了其在氧还原反应(ORR)的催化的活性和电子转移历程。结构表征表明,制备的GOFs的形貌显示出明显的层状结构,层间距提高了0.45?,TGA结果表明热稳定性增强,比表面积显著提高,说明氧化石墨烯插层结构被成功制备。性能分析表明GOFs可用于催化双氧水的电化学合成,且具有选择性高、绿色环保、成本较低等优势。2.以氧化石墨烯为原料,通过水热反应,制备了自组装石墨烯,并以此为基础,通过有机溶液置换、直接冷冻干燥以及PECVD生长等多种手段,制备了多种三维石墨烯复合材料,主要包括:氧化石墨烯直接自组装得到的水凝胶,有机溶剂置换并冻干后得到的三维石墨烯气凝胶,PECVD生长的石墨烯纳米墙和氧化石墨烯复合自组装,以三维石墨烯气凝胶为基底生长石墨烯纳米墙复合材料。通过一系列表征手段,分析了其结构与性能特点。通过改良设计路线得到了三维石墨烯气凝胶以及它与石墨烯纳米墙的复合材料,具有疏松规整的三维孔结构,比表面积提高到了795 m2/g,提高了近两倍。三维石墨烯气凝胶的氢气存储质量密度高达5.5%。
[Abstract]:Graphene is a hexagonal honeycomb two-dimensional atomic crystal formed by carbon atom sp2 hybrid. Its special two-dimensional structure makes it have excellent properties in many aspects, such as electrical conductivity, thermal conductivity and so on. To some extent, the application of graphene is limited by two-dimensional materials. The interaction between graphene and solvent is weak, and the strong conjugate structure of two dimensional makes the van der Waals force between layers very strong, forming a bond with a distance of 0.34 nm. Therefore, graphene is easy to pile up but difficult to peel and disperse, which brings great difficulties to the further processing and application of graphene functional materials. Not only are they easily dispersed in a variety of solvents, but they can also be reduced to graphene, so they are by far the most widely studied derivatives of graphene. Similar to graphite, graphite oxide also maintains a layered structure. After strongly acidic and strongly oxidized solvents, the graphite lamellae has introduced many different oxygen-containing functional groups, such as hydroxyl, epoxy, carbonyl and carboxyl, etc. That is graphene oxide. And because the layered structure is easily dispersed into the solvent, the pore structure is well protected. Using the unique properties of graphene oxide, the two-dimensional materials are assembled into three-dimensional graphene nanocomposites. It can solve the difficulties in the application of two-dimensional materials and has great significance for the basic and applied research of graphene. Therefore, this paper mainly focuses on the properties of oxygen functional groups and pore structures. A variety of three-dimensional porous graphene nanocomposites have been studied. The main contents and results of this paper are as follows: 1. Using graphene oxide as the main raw material, the oxygen-containing functional groups between graphene oxide layers are used to react with different boric acid derivatives. Three different intercalation structures have been successfully prepared. The framework structure of graphene oxide (GFA) was obtained by adding lithium to the GOF, which was used as the bonding agent for p-carboxyphenylboric acid. The GOF was not prepared by means of scanning electron microscope (SEM), X-ray diffraction (XRD), nitrogen adsorption test and thermogravimetric analysis (TGA). The same knot hook was analyzed. The catalytic activity and electron transfer mechanism of the prepared GOFs in oxygen reduction reaction orr were analyzed by electrochemical analysis. The structure characterization showed that the morphology of the prepared GOFs showed obvious layered structure, and the interlayer spacing was increased by 0.45? The results showed that the thermal stability was enhanced and the specific surface area was significantly improved, which indicated that the graphene oxide intercalation structure was successfully prepared. The performance analysis showed that GOFs could be used to catalyze the electrochemical synthesis of hydrogen peroxide with high selectivity and environmental protection. 2. Using graphene oxide as raw material, self-assembled graphene was prepared by hydrothermal reaction. On the basis of this, various methods such as replacement of organic solution, direct freeze-drying and PECVD growth were used. A variety of three dimensional graphene composites were prepared, including hydrogels prepared by direct self-assembly of graphene oxide. Three dimensional graphene aerogels grown by PECVD were prepared by replacing and freeze-drying with organic solvents. The composite self-assembly of graphene nanowall and graphene oxide was carried out. Three dimensional graphene aerogel was used as substrate to grow graphene nanowall composites. The structure and properties were analyzed. Through the improved design route, the three-dimensional graphene aerogel and its composites with graphene nanowall were obtained. The specific surface area was increased to 795 m2 / g, nearly twice as much. The hydrogen storage mass density of three dimensional graphene aerogels was up to 5.5%.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.11;TB33

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