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

火焰合成完全石墨化的碳纳米纤维和含有包裹金属颗粒的纳米纤维复合材料这一探索性研究的小额资助涉及火焰合成含有包裹金属颗粒的完全石墨化的碳纳米纤维。 碳纳米结构，如纳米管和纳米纤维，具有优异的性能（毛细作用，机械强度，金属或半导体行为，金属颗粒的封装和储氢能力）。 然而，几乎没有生产大量高纯度定向纳米管或纳米纤维的技术。 燃烧合成这些纳米材料是一种有吸引力的方法。 已经表明，有可能将周期性金属沉积物包封在纳米纤维中。 含有催化颗粒的纳米结构可以作为有效的纳米级反应器。金属颗粒的包封还可以使CNF物理或化学官能化以用于有用的目的，并形成连接的CNF网络。 拟议项目的目标是将各种金属纳米颗粒封装在通过火焰合成产生的完全石墨化的纳米纤维和纳米网络中。 该研究审查是否：（1）可以合成具有特定长度和螺旋度的完全石墨化的碳纳米纤维作为具有和不具有异质结的纯物种（2）可以开发自组装技术，例如通过使用各种催化剂基底，以控制纳米级组分的相对排列，从而实现预先设计的排列和形态;和（3）可以表征导致经济地制备纳米结构的方法，并控制尺寸和形状以用于应用。 所使用的反应器在多孔介质燃烧器的出口处稳定富燃料火焰。 热的热解气体撞击在衬底上。 影响这些纳米材料的火焰合成的实验矩阵包括基板材料，燃料/空气当量比，基板温度，以及流速和停留时间。更广泛的影响这个项目具有经济意义，以及那些为提高知识。虽然碳纳米结构的研究是一个快速发展的领域，但由于缺乏大量经济地生产这种材料的方法，商业化受到阻碍。 对火焰合成有序碳纳米结构（如CNF和CNT）的理解仍处于早期阶段。 该项目有助于一名国家科学基金会研究生的教育和一名研究助理的学术和研究培训。

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.