基于密度泛函理论对低维功能化纳米材料结构和性质的第一性原理研究

发布时间：2018-01-15 23:32

本文关键词：基于密度泛函理论对低维功能化纳米材料结构和性质的第一性原理研究　出处：《青岛大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,低维纳米材料的合成和性质的研究成为国内外的热点研究领域,引起了人们的广泛关注。利用多种方式对低维纳米材料进行修饰和改造,拓宽其应用领域是人们关注的焦点。从理论上研究修饰纳米材料的结构和性质将对于其在实验和工业化上的应用有着指导性的意义。本文采用密度泛函理论对羧基修饰的碳纳米材料和锗烯-二硫化钼异质结的结构和性质进行了系统的理论研究,以期对实验和工业化利用相关纳米材料提供合理化建议。首先,本文使用M05-2X/6-31G*方法研究了羧基修饰的扶手椅型(n,n)和锯齿形(n,0)单壁碳纳米管和石墨烯的酸性。基于密度泛函理论结合热力学循环方法对羧基功能化的碳纳米管和石墨烯的酸性强度进行预测,着重分析了碳纳米管的直径、长度、手性、缺陷以及羧基官能团修饰位置对功能化的碳纳米管在气相和液相中的酸性的影响,并与羧基功能化的石墨烯的酸性强度进行比较。理论预测得到的pKa数据将为羧基功能化的低维碳材料在不同领域的应用拓展提供指导。其次,利用GGA-PBE方法对锗烯-二硫化钼异质结的结构和电子性质进行了研究,并重点考察了外加垂直电场的影响。结果表明锗烯与二硫化钼之间的范德华作用可以成功的打开锗烯的带隙,但又能有效的保持两种材料的电子性质。调节外加电场的方向和强度可以对带隙的大小进行有效的调控,并可以改变两者之间电荷转移的方向和强度。对该异质结性质的深入理解可为其在场效应晶体管方面的应用提供指导。最后,在B97D-6-31G*水平下研究了氨基修饰的碳纳米管的几何和电子结构。研究了氨基修饰对于碳纳米管的结构和电荷分布的影响。
[Abstract]:In recent years, the research on the synthesis and properties of low-dimensional nanomaterials has become a hot research field at home and abroad, which has attracted extensive attention. The low-dimensional nanomaterials are modified and modified in various ways. The study of the structure and properties of modified nanomaterials in theory will be of guiding significance for their application in experiments and industrialization. In this paper, the density functional theory (DFT) is used to study carboxylic acid. The structure and properties of carbon nanomaterials and germane-molybdenum disulfide heterostructures were systematically studied. In order to provide reasonable suggestions for the experimental and industrial use of related nanomaterials. Firstly, the armchair type modified by carboxyl group was studied by M05-2X / 6-31G* method. Based on density functional theory (DFT) and thermodynamic cycle method, the acidity of carboxyl functionalized carbon nanotubes and graphene was predicted. The effects of the diameter, length, chirality, defects and the modification position of carboxyl functional groups on the acidity of functionalized CNTs in gas and liquid phase were analyzed. And compared with the carboxyl functionalized graphene acid strength. The predicted pKa data will provide guidance for the application of carboxyl functionalized low-dimensional carbon materials in different fields. Secondly. The structure and electronic properties of germane-molybdenum disulfide heterojunction were studied by GGA-PBE method. The results show that the van der Waals interaction between germane and molybdenum disulfide can successfully open the band gap of germanium. But it can effectively maintain the electronic properties of the two materials. Adjusting the direction and strength of the external electric field can effectively regulate the size of the band gap. The direction and intensity of charge transfer between the two can be changed. The further understanding of the properties of the heterojunction can provide guidance for the application of the field-effect transistors. The geometry and electronic structure of amino-modified carbon nanotubes were studied at B97D-6-31G * level, and the effects of amino modification on the structure and charge distribution of carbon nanotubes were studied.
【学位授予单位】：青岛大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O641.1

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