【作者】 关磊；

【导师】 崔屾；

【作者基本信息】 天津大学 ， 物理化学， 2010， 博士

【摘要】 新型碳纳米材料包括纳米颗粒、管、棒、带、膜以及三维结构等,具有优异的电学、力学性能以及热学性能,显示出很好的应用前景,已经成为纳米材料研究领域的前沿和热点之一。本文采用直流电弧放电法,以铁、钴、镍的氧化物为催化剂,考察了高温氮气对阴极顶端电弧放电沉积产物的影响;还考察了碳源、进气温度、基底及其放置位置对其表面沉积产物的形貌、微观结构以及组成的影响。TEM和HRTEM表征结果表明,具有不同形貌特征的大直径碳管存在于阴极顶端柱状产物外围的刺状产物中;SAED和EDX表征结果表明,氮和过渡金属元素是以高分散的形式进入了大直径碳管;HRTEM和Raman表征结果表明,3-8层的石墨烯纳米片存在于柱状产物的内芯中,产率可达50 wt.%;XRD和EDX表征结果表明,石墨烯纳米片是氮掺杂的,过渡金属可能以高分散的形式存在于石墨烯纳米片中。SEM表征结果表明,对于放置在电弧放电区域的上面、侧面和下面的基底来说,氮气进气温度和碳源对不锈钢、石英和硅(100)基底上生成的产物的形貌的影响程度逐渐减小,其产物从准三维网状结构的膜状碳产物过渡到比较致密的碳颗粒构成的膜状碳产物;基底的种类对其表面生成的产物的形貌有一定的影响,但没有明显的规律性;对于不锈钢、石英和硅(100)基底来说,在氮气进气温度和碳源均相同的条件下,基底放置在电弧放电区域的上面、侧面和下面对其表面沉积产物的形貌的影响程度逐渐增加,其产物从准三维网状结构的膜状碳产物过渡到比较致密的碳颗粒构成的膜状碳产物。TEM表征结果表明,放置于电弧放电区域上面、侧面和下面的不锈钢、石英和硅(100)基底上生成的膜状碳产物均主要由碳纳米颗粒或碳颗粒构成。根据SEM、TEM以及HRTEM表征结果,推断准三维网状结构碳产物均由碳纳米颗粒构成。分别对大直径碳管、石墨烯纳米片以及准三维网状结构的生成机理进行了讨论。本文的研究结果对于新型碳膜的制备与纳米材料制备的分子设计以及电弧放电化学的发展不仅提供了重要的实验依据,而且具有一定的理论意义。更多还原

【Abstract】 Novel carbon nanomaterials include nanoparticles, nanotubes, nanorods, nanoribbons, nanofilms, and three-dimensional (3D) nanostructures. They have excellent electrical, mechanical and optical properties, showing good prospect of applications, and become one of the forefront and hot topics of nanomaterial research.In this thesis, DC arc discharge method was employed and the iron, cobalt and nickel oxides were used as the catalysts. The effect of the high temperature nitrogen gas on the deposits formed on the top of the cathode was investigated. The effects of carbon sources, the temperature of nitrogen gas, substrates and their positions on the morphologies, microstructures and composition of the films formed on the surfaces of substrates were also investigated.The results of TEM and HRTEM characterizations show that the large diameter carbon tubes (LDCTs) with different morphologies were formed in the spinous products around the column-shaped product deposited on the top of the cathode. The results of SAED and EDX characterizations show that the LDCTs were doped with the nitrogen and transition metal elements. The results of HRTEM and Raman characterizations show that the 3-8 layer graphene nanosheets were formed in the inner core of the column-shaped product and their yield was up to 50 wt. %. The results of XRD and EDX characterizations show that the graphene nanosheets were doped with nitrogen, and may be also doped with the transition metal elements.The results of SEM characterization show that when the substrates were put above, at one side of, and under the arc discharge region, the effects of the temperature of nitrogen gas and carbon sources on the morphologies of the films formed on the stainless steel, quartz and Si(100) substrates gradually reduced, and the morphologies of the carbon films changed from the quasi-3D netlike structure to the dense film composed of carbon particles; and the effect of the substrates, which included stainless steel, quartz and Si(100) substrates, on the morphologies of the films formed on their surfaces was not very obvious and without the remarkable regularity. Under the same conditions of the temperature of nitrogen gas and carbon source, the effects of the positions of the stainless steel, quartz and Si(100) substrates, which were put above, at one side of, and under the arc discharge region, on the morphologies of the films formed on their surfaces gradually increased, and the morphologies of the carbon films also changed from the quasi-3D netlike structure to the dense film composed of carbon particles. The results of TEM characterization show that the carbon films formed on stainless steel, quartz and Si(100) substrates, which were put above, at one side of, and under the arc discharge region, mainly consist of carbon nanoparticles or carbon particles. It is deduced from the results of SEM, TEM and HRTEM characterizations that the quasi-3D netlike structure is mainly composed of carbon nanoparticles. The formation mechanisms of the LDCT, graphene nanosheet and quasi-3D netlike structure were discussed, respectively.The results in this thesis not only provide an important experimental basis, but also have some theoretical significance for the preparation of novel carbon films, the molecular design of carbon nanomaterials and the development of arc discharge chemistry.更多还原