基于尺寸可控氧化石墨烯片层的三维宏观石墨烯的结构与性质调控研究

发布时间：2018-06-28 03:06

本文选题：氧化石墨烯 + 尺寸分离　；参考：《华东师范大学》2017年硕士论文

【摘要】：石墨烯是碳原子以六边形紧密堆积形成的二维原子晶体,具有特殊的物理化学性质,在工业催化、储能器件和生物医学等诸多领域均展现出巨大的应用潜能。将石墨烯组装成稳定的、具有规则形状的宏观体材料是推动石墨烯走向实际应用的重要步骤,而氧化石墨烯作为石墨烯宏观材料的前驱体是其研究的重点。本论文以目数不同的鳞片石墨为原料,基于氧化石墨烯片层在酸性溶液中分散性的差异,分离得到尺寸、浓度可控的氧化石墨烯溶液,以其为前驱体,实现了三维石墨烯在不同尺度上的可控制备;考察了三维石墨烯的结构、催化性质和机械性能,建立氧化石墨烯的微观片层尺寸与三维石墨烯的宏观结构和性质的对应关系。主要研究成果如下:1、可控片层氧化石墨烯的制备及其片层尺寸与三维石墨烯结构和催化性能的关系研究采用目数不同的鳞片石墨作为原料,以低速离心的方法分离制备获得大、中、小三种片层尺寸的氧化石墨烯溶液。研究了氧化石墨烯片层尺寸对溶液的分散程度、微观结构和堆叠行为的影响。通过对三种片层氧化石墨烯气凝胶的SEM、XRD、Raman等表征可以看出较大片层的氧化石墨烯气凝胶有孔状结构,片层间距较大。以三种片层氧化石墨烯溶液为前驱体制备了三维石墨烯材料,研究了氧化石墨烯片层尺寸对其比表面积、微观孔结构的影响。数据表明,氧化石墨烯片层越大,三维石墨烯的比表面积,孔径,体积随之增大。以具有大比表面积的三维石墨烯作为载体负载金属铂纳米颗粒制备新型复合催化剂,以经典的对硝基苯酚的还原反应作为测试催化剂活性的模型反应。从金属负载量与金属负载颗粒尺寸两个方面研究氧化石墨烯片层尺寸对复合催化剂活性的影响。结果表明,氧化石墨烯片层越小,含氧基团数目越多,金属的实际负载量越大,粒径分布越窄,催化性能越好。2、可控片层氧化石墨烯液晶态的制备及其有序性与三维石墨烯结构和机械性能的关系研究结合第一部分的研究内容,将制备分离得到的小、中和大片氧化石墨烯溶液做进一步处理,发挥其相应的片层优势。以片层均匀的中片和大片氧化石墨烯为前体,制备了低浓度向列型液晶态氧化石墨烯,采用化学还原方法,将其转化为三维石墨烯宏观材料。液晶态氧化石墨烯溶液的片层取向转变为三维石墨烯海绵有序的微观结构,通过大尺寸氧化石墨烯片层液晶态的有序排列优化三维石墨烯的网络结构和力学性能。得到拥有大范围有序网络孔结构的弹性三维石墨烯海绵。将氧化石墨烯片层尺寸与三维石墨烯微观结构有序性相联系,用以研究三维石墨烯海绵微观结构与机械性能的关系。得出结论,氧化石墨烯溶液中片层排列越有序,相应的气凝胶中孔结构越整齐,还原后的三维石墨烯的网络结构范围愈大,其机械性能越好。
[Abstract]:Graphene is a two-dimensional atomic crystal formed by hexagonal compact stacking of carbon atoms. It has special physical and chemical properties and has shown great application potential in many fields such as industrial catalysis energy storage devices biomedicine and so on. Assembling graphene into stable and regular macrobulk materials is an important step to promote the practical application of graphene, and graphene oxide as the precursor of graphene macroscopical material is the focus of its research. In this paper, graphene oxide solution with controllable size and concentration was obtained by using flake graphite with different mesh number as raw material, based on the dispersion of graphene oxide in acid solution. The controllable preparation of 3D graphene at different scales was realized, the structure, catalytic properties and mechanical properties of 3D graphene were investigated, and the corresponding relationship between the microlamellar size of graphene oxide and the macroscopic structure and properties of 3D graphene was established. The main research results are as follows: 1. The preparation of controllable graphene oxide and the relationship between its lamellar size and the structure and catalytic performance of three-dimensional graphene. The scale graphite with different mesh number was used as raw material, and the separation and preparation of graphene by low speed centrifugation was carried out. Three small lamellar sizes of graphene oxide solution. The effects of the size of graphene oxide on the dispersion, microstructure and stacking behavior of the solution were studied. Through the characterization of the three lamellar graphene oxide aerogels, we can see that the larger lamellar graphene oxide aerogels have pore structure and larger lamellar spacing. Three dimensional graphene materials were prepared by using three kinds of graphene oxide solution as precursors. The effect of the size of graphene oxide lamellar on the specific surface area and microstructure of graphene oxide was studied. The results show that the larger the graphene oxide lamellar, the larger the surface area, pore size and volume of 3D graphene. A new type of composite catalyst was prepared by using three-dimensional graphene with large specific surface area as the carrier supported on platinum nanoparticles. The classical reduction reaction of p-nitrophenol was used as the model reaction to test the activity of the catalyst. The effect of graphene oxide lamellar size on the activity of the composite catalyst was studied from the aspects of metal loading and metal supported particle size. The results show that the smaller the graphene oxide lamellae, the more the number of oxygen groups, the larger the actual load of metal and the narrower the particle size distribution. The better the catalytic activity is, the better the preparation of liquid crystal state of controllable lamellar graphene oxide and the relationship between its orderliness and the structure and mechanical properties of three-dimensional graphene are combined with the research contents of the first part, the preparation and separation of the liquid crystal state of graphene oxide are small. Neutralize a large amount of graphene oxide solution for further treatment, giving play to its corresponding lamellar advantages. Low concentration nematic liquid crystalline graphene oxide was prepared by chemical reduction method. The lamellar orientation of liquid crystalline graphene oxide solution changed to the ordered microstructure of three-dimensional graphene sponge. The network structure and mechanical properties of three-dimensional graphene oxide were optimized by the ordered arrangement of liquid crystal state of large size graphene oxide lamellar. An elastic three dimensional graphene sponge with a wide range of ordered network pore structures was obtained. In order to study the relationship between the microstructure and mechanical properties of 3D graphene sponge, the size of graphene oxide lamellar is related to the order of three-dimensional graphene microstructure. It is concluded that the more ordered the lamellar arrangement in graphene oxide solution, the more neat the pore structure of the aerogel is, and the larger the network structure of the reduced three dimensional graphene is, the better its mechanical properties are.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.71

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