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

火焰合成全石墨碳纳米纤维和含包封金属颗粒的纳米纤维复合材料摘要：本探索性研究小额资助涉及火焰合成含包封金属颗粒的全石墨碳纳米纤维。碳纳米结构，如纳米管和纳米纤维，具有优异的性能（毛细性、机械强度、金属或半导体性能、金属颗粒的封装和储氢能力）。然而，目前很少有技术可以大批量生产高纯度的排列纳米管或纳米纤维。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，在纳米纤维中封装周期性金属沉积是可能的。含有催化颗粒的纳米结构可以作为高效的纳米反应器。金属颗粒的封装也可以使CNF在物理或化学上功能化，并形成连接的CNF网络。该项目的目标是将各种金属纳米粒子封装在通过火焰合成产生的完全石墨纳米纤维和纳米纤维网络中。该研究考察了：(1)具有特定长度和螺旋度的完全石墨碳纳米纤维是否可以合成为具有或不具有异质结（使纳米纤维网络成为可能）的纯种；(2)可以开发自组装技术，例如通过使用各种催化剂衬底来控制纳米级组件的相对排列，以实现预先设计的排列和形态；(3)有可能表征导致经济制备纳米结构的过程，并控制其尺寸和形状用于应用。该反应堆用于稳定多孔介质燃烧器出口的富燃料火焰。热裂解气体撞击基底。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。更广泛的影响：该项目具有经济意义，也有助于增进知识。尽管对碳纳米结构的研究是一个快速发展的领域，但由于缺乏经济批量生产这种材料的方法，商业化受到了阻碍。对火焰合成有序碳纳米结构（如CNFs和CNTs）的认识尚处于早期阶段。该项目有助于培养一名NSF研究生，并为一名研究助理提供学术和研究培训。

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.