六方氮化硼和石墨烯的制备及表界面物理力学研究

发布时间：2018-12-20 22:37

【摘要】：二维原子晶体材料具有的平面层状结构和优异的物理力学性质使得其成为近些年的研究热点。大面积高质量单层石墨烯和六方氮化硼的可控生长和转移是研究其宏观性质及应用的基础。这里我们以石墨烯和六方氮化硼两种二维原子晶体材料为主,面向宏观功能应用,通过化学气相沉积方法制备大面积高质量单层石墨烯和六方氮化硼,针对其功能涂层性质、亲疏水性、多层石墨烯的气流致生电效应以及氧化锌纳米薄膜中的波动势进行了系统深入地研究,取得如下主要研究进展:1.单层六方氮化硼的可控生长及其抗氧化、减摩擦的涂层性质:我们系统地研究了六方氮化硼在铜孪晶上的化学气相沉积行为。发现在无氧环境下六方氮化硼倾向于在孪晶窄带上生长。引入氧可以有效抑制这种选择性,实现均匀生长。第一性原理计算揭示其原因是氧辅助下前驱物分子的脱氢能垒的降低。此外,我们发现通过化学气相沉积法生长的高质量大面积单层六方氮化硼能显著的调节基底表面的摩擦、氧化以及绝缘性能。结合六方氮化硼高的热稳定性及化学稳定性,这些优异的涂层性质使其在功能涂层材料方面具有重要应用价值。2.六方氮化硼和石墨烯与基底材料无关的独特润湿性能:我们研究揭示出新生长的六方氮化硼薄膜的接触角和基底材料以及六方氮化硼层数无关。第一性原理计算和范德华作用分析证实单层六方氮化硼可以有效地调节水分子和不同基底间的作用,而使得不同基底材料具有表观趋同的疏水性。暴露在空气中后,由于表面吸附空气中的有机分子,六方氮化硼和石墨烯的接触角都会单调增加,很快达到一个与基底材料无关的饱和值。这一饱和接触角对基底材料、层数以及溶液离子种类等多个因素的变化都几乎没有响应,并在长达八个月的实验跨度内保持不变,显示了其润湿统一性和稳定性。这一特殊的单原子层覆层的润湿性质具有重要的实用性。3.多层石墨烯的Seebeck系数与气流致生电以及氧化锌纳米薄膜的波动势:我们发现通过转移-堆叠制备的1-8层石墨烯Seebeck系数在第六层时达到最大值,是单层石墨烯的1.8倍,而其气流致生电电压在第五层达到最大值,是单层石墨烯的1.9倍。我们在石墨烯之外的材料体系中首次观察到波动势效应,发现含离子的溶液表面沿柔性透明的氧化锌纳米薄膜波动时会产生电压。氧化锌薄膜中这种感应电压会随着运动速度线性增加,开路电压可达数十毫伏,短路电流可达微安级别。此外,这种感应生电可以通过串并联有效放大。理论模拟表明氧化锌纳米薄膜较低的载流子浓度和迁移率使其和其他金属性纳米薄膜相比在收集环境能方面有着明显的优势。
[Abstract]:The planar layered structure and excellent physical and mechanical properties of two-dimensional atomic crystal materials make it a hot research topic in recent years. The controlled growth and transfer of large area and high quality monolayer graphene and hexagonal boron nitride are the basis for studying their macroscopic properties and applications. Here we mainly use graphene and hexagonal boron nitride two kinds of two dimensional atomic crystal material, face macroscopical function application, through chemical vapor deposition method to prepare large area high quality monolayer graphene and hexagonal boron nitride, according to its function coating property, Hydrophobicity, airflow generation effect of multilayer graphene and fluctuation potential in ZnO nanocrystalline films have been studied systematically and deeply. The main research progress is as follows: 1. Controlled growth of single layer hexagonal boron nitride and its antioxidation and antifriction properties: we have systematically studied the chemical vapor deposition behavior of hexagonal boron nitride on copper twin. It is found that hexagonal boron nitride tends to grow on twin narrow band in anaerobic environment. Introduction of oxygen can effectively inhibit this selectivity and achieve uniform growth. The first principle calculation shows that the reason is the decrease of dehydrogenation barrier of the precursor molecule assisted by oxygen. In addition, we found that the high quality monolayer hexagonal boron nitride grown by chemical vapor deposition can significantly regulate the friction, oxidation and insulation properties of the substrate surface. Combined with the high thermal and chemical stability of hexagonal boron nitride, these excellent coatings have important application value in functional coating materials. 2. The unique wettability of hexagonal boron nitride and graphene independent of substrate material: we have revealed that the contact angle of the newly grown hexagonal boron nitride film is independent of the substrate material and the number of hexagonal boron nitride layers. First-principles calculation and van der Waals interaction analysis show that monolayer hexagonal boron nitride can effectively regulate the interaction between water molecules and different substrates, which makes different substrates have apparent hydrophobicity. After exposure to air, the contact angle of hexagonal boron nitride and graphene increases monotonously due to the adsorption of organic molecules in air on the surface, and soon reaches a saturation value independent of the substrate material. The saturated contact angle is almost unresponsive to the changes of substrate material, number of layers and the species of ions in the solution, and remains constant throughout the experimental span of up to eight months, showing its wetting uniformity and stability. The wetting properties of this special monatomic coating have important practicability. The Seebeck coefficient of multilayer graphene, gas generated electricity and the fluctuating potential of ZnO nanocrystalline films are found to be the highest at the sixth layer, which is 1.8 times higher than that of the monolayer graphene, and the Seebeck coefficient of 1-8 layer graphene prepared by transfer stacking is up to the maximum at the sixth layer. The electrogeneration voltage in the fifth layer is 1.9 times higher than that of the graphene monolayer. The wave potential effect was observed for the first time in a material system other than graphene. It was found that the voltage was generated when the surface of the solution containing ions fluctuated along the flexible and transparent ZnO nanocrystalline film. The inductive voltage in ZnO film increases linearly with the velocity of motion, the open circuit voltage can reach tens of millivolts, and the short circuit current can reach the microampere level. In addition, the inductive generation can be effectively amplified in series and parallel. Theoretical simulation shows that zinc oxide nanocrystalline films have obvious advantages in collecting environmental energy compared with other gold nanofilms due to their low carrier concentration and mobility.
【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O48;TB383.1

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