石墨烯、掺杂石墨烯的制备及其电化学性能研究

发布时间：2018-05-28 12:16

  本文选题：氟化石墨 + 石墨烯　； 参考：《兰州理工大学》2017年硕士论文

【摘要】：石墨烯是一种由单层碳原子紧密排列成二维蜂窝状结构的碳材料。石墨烯展现出很多优异的物理化学性能,从发现开始就受到各个领域的广泛关注。然而,石墨烯仍然存在一些不足。例如,石墨烯片层易发生团聚,采用化学剥离法制备的石墨烯缺陷多。此外,石墨烯是一种能带隙为零的半导体,一定程度上限制了石墨烯应用于电学器件。研究表明,通过化学掺杂可以有效调节石墨烯的电子结构,改善其物理化学性质。基于以上问题,本论文采用石墨以及氟化石墨为原料,通过不同方法制备石墨烯及掺杂石墨烯,考察所得石墨烯及掺杂石墨烯的形貌、结构、电导率及电化学性能。主要研究内容包括以下几个方面:(1)以石墨为原料,通过三种不同的氧化方法制备氧化石墨烯(Graphene O xide,GO),以水合肼为还原剂将GO还原为石墨烯,考察GO氧化程度对石墨烯在有机溶剂中分散性能及电化学性能的影响。结果表明,调控氧化剂的用量和种类,可以改变GO的氧化程度;以氧化程度最高的GO还原所得的石墨烯,在有机溶剂中的分散性能最好,电化学性能最佳。(2)化学剥离法是以石墨为原料,通过氧化和还原过程制备石墨烯,由于存在过度氧化以及不彻底还原,所得石墨烯存在较多的结构缺陷,进而影响石墨烯的性能。因此,选用氟化石墨为原料,通过超声法,静置法以及加热回流法三种方法制备石墨烯,对所得石墨烯进行形貌、结构表征及电化学性能测试。结果表明,三种方法均可制备出单晶结构的石墨烯,其中加热回流法制备的石墨烯晶体有序度最高,电化学性能最佳。(3)以氟化石墨为原料,尿素为氮源,通过高温固相反应制备氮掺杂石墨烯(N-Gr),探讨了反应温度对N-Gr的结构及电化学性能的影响。结果表明,氮元素以吡咯氮、吡啶氮和石墨化氮三种形式掺入石墨烯晶格结构中。500℃下制备的N-Gr具有最佳的电化学性能,此外,其电导率可达9475 S/m,远远大于以GO为原料在相同条件下制备的氮掺杂石墨烯(N-RGO)的电导率(200 S/m)。(4)以氟化石墨为原料,Na HSO3、Na2S2O3·5H2O、Na2SO3以及N a2S·9H2O为硫源,采用高温固相反应制备硫掺杂石墨烯(S-Gr),探讨不同硫源对S-Gr的结构及电化学性能影响。结果表明,硫元素以C-S-C、C-SOx-C两种结构掺杂进入石墨烯晶格结构中。其中以Na2S·9H2O作为掺杂剂制备的硫掺杂石墨烯的硫含量最高(3.35%),电导率最高(21720 S/m),电化学性能最佳。
[Abstract]:Graphene is a kind of carbon material which consists of a single layer of carbon atoms tightly arranged into two-dimensional honeycomb structure. Graphene shows many excellent physical and chemical properties, and has attracted wide attention from the beginning of its discovery. However, there are still some deficiencies in graphene. For example, graphene laminates are easy to be agglomerated, and many graphene defects are produced by chemical stripping method. In addition, graphene is a kind of semiconductor with zero band gap, which limits the application of graphene to electrical devices to some extent. The results show that the electronic structure of graphene can be adjusted and its physical and chemical properties can be improved by chemical doping. Based on the above problems, graphene and graphene doped with graphite and graphite fluoride were prepared by different methods. The morphology, structure, conductivity and electrochemical properties of graphene and doped graphene were investigated. The main research contents include the following aspects: (1) Graphene oxide O xidegol was prepared by three different oxidation methods using graphite as raw material, and go was reduced to graphene by hydrazine hydrate. The effects of go oxidation degree on the dispersion and electrochemical properties of graphene in organic solvents were investigated. The results showed that the oxidation degree of go could be changed by adjusting the amount and type of oxidant, and the graphene reduced by go with the highest degree of oxidation had the best dispersion in organic solvent. The method of chemical stripping is to prepare graphene from graphite by oxidation and reduction. Because of excessive oxidation and incomplete reduction, there are many structural defects in the obtained graphene. Furthermore, the properties of graphene are affected. Therefore, graphite fluoride was used as raw material to prepare graphene by ultrasonic method, static method and heating reflux method. The morphology, structure and electrochemical properties of the obtained graphene were characterized. The results showed that graphene with single crystal structure could be prepared by the three methods. Among them, the order degree of graphene prepared by heating reflux method was the highest, and the electrochemical performance of graphene was the best. The graphite fluoride was used as raw material and urea as nitrogen source. N-doped graphene N-Gr-O was prepared by solid state reaction at high temperature. The effect of reaction temperature on the structure and electrochemical properties of N-Gr was investigated. The results show that the N-Gr doped with pyrrole nitrogen, pyridine nitrogen and graphitized nitrogen into graphene lattice structure at .500 鈩，

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