Flame Synthesis of Completely Graphitic Carbon Nanofibers and Nanofiber Composites Containing Encapsulated Metal Particles

火焰合成完全石墨化碳纳米纤维和含有包裹金属颗粒的纳米纤维复合材料这项探索性研究的小额赠款属于火焰合成包含包裹金属颗粒的完全石墨化碳纳米纤维。碳纳米结构，如纳米管和纳米纤维，具有突出的性能(毛细、机械强度、金属或半导体行为、金属颗粒的包裹和储氢能力)。然而，几乎没有技术可以批量生产高纯度的定向纳米管或纳米纤维。燃烧合成这些纳米材料是一种很有吸引力的方法。研究表明，在纳米纤维中包裹周期性的金属沉积是可能的。含有催化颗粒的纳米结构可以作为高效的纳米级反应器。金属颗粒的包裹也可以使碳纳米纤维物理或化学功能化以达到有用的目的，并形成连接的碳纳米纤维网络。拟议项目的目标是将各种金属纳米颗粒封装在完全石墨化的纳米纤维和通过火焰合成产生的纳米纤维网络中。这项研究考察了是否：(1)指定长度和螺旋度的完全石墨化碳纳米纤维可以作为纯物种合成，有或没有异质结(使纳米纤维网络成为可能)；(2)可以开发自组装技术，例如通过使用各种催化剂底物来控制纳米组件的相对排列，以实现预先设计的排列和形貌；以及(3)有可能表征导致经济地制备纳米结构的过程，并控制应用的尺寸和形状。所使用的反应堆稳定了多孔介质燃烧器出口处富含燃料的火焰。热解气体撞击在衬底上。影响这些纳米材料火焰合成的实验基质包括衬底材料、燃料/空气当量比、衬底温度、流速和停留时间。尽管碳纳米结构的研究是一个快速发展的领域，但由于缺乏经济地批量生产这种材料的方法，商业化受到阻碍。对碳纳米管、碳纳米管等有序碳纳米结构的火焰合成的认识还处于早期阶段。该项目有助于对一名国家科学基金会研究生进行教育，并对一名研究助理进行学术和研究培训。

FLAME SYNTHESIS OF COMPLETELY GRAPHITIC CARBON NANOFIBERS ANDNANOFIBER COMPOSITES CONTAINING ENCAPSULATED METAL PARTICLESABSTRACTThis Small Grant for Exploratory Research pertains to the flame synthesis of completely graphitic carbon nanofibers that contain encapsulated metal particles. Carbon nanostructures, such as nanotubes and nanofibers, possess outstanding properties (capillarity, mechanical strength, metallic or semiconducting behavior, encapsulation of metal particles, and hydrogen storage capability). However, there are few technologies for producing bulk quantities of high-purity aligned nanotubes or nanofibers. The combustion synthesis of these nanomaterials is an attractive method. It has been shown that it is possible to encapsulate periodic metal deposits in the nanofibers. Nanostructures containing catalytic particles could serve as efficient nanoscale reactors. The encapsulation of metal particles may also make it possible to physically or chemically functionalize CNFs for useful purposes, and to form connected CNF networks. The objective of the proposed project is to encapsulate a variety of metal nanoparticles in completely graphitic nanofibers and nanofiber networks that are produced through flame synthesis. The study examines if: (1) completely graphitic carbon nanofibers of specified length and helicity can be synthesized as pure species both with and without heterojunctions (that enable nanofiber networks); (2) self-assembly techniques can be developed, say by using a variety of catalyst substrates, to control relative arrangements of nanoscale components to enable predesigned arrangements and morphologies; and (3) it is possible to characterize the processes that lead to economic preparation of nanostructures with control over size and shape for applications. The reactor used stabilizes a fuel-rich flame at the exit of a porous-media burner. The hot pyrolysis gases impinge on a substrate. The experimental matrix that influences the flame synthesis of these nanomaterials includes the substrate material, fuel/air equivalence ratio, substrate temperature, and the flow velocity and residence time.Broader impactThis project has economic implications as well as those for the enhancement of knowledge. Although research on carbon nanostructures is a fast-moving field, commercialization is hampered by the lack of methods to economically produce the material in bulk. The understanding of the flame synthesis of ordered carbon nanostructures, such as CNFs and CNTs, is still at an early stage. The project contributes to the education of an NSF graduate fellow and the academic and research training of a research associate.