NER: Theoretical and Experimental Investigations of Catalyzed Single-Walled Carbon Nanotubes Growth

单壁碳纳米管具有特殊的化学和电学性质，使其在纳米技术、生物和医学等领域具有极大的吸引力。这些有趣的性质强烈依赖于纳米管的特殊结构。这项研究的目标是微调合成过程，只生产具有所需直径和化学特性的单壁碳纳米管。基于含碳气体在金属纳米催化剂分散体上的流动，已经开发出一种满足这些目标的精细合成工艺。这种微小的金属颗粒催化气体分解，产生碳原子，这些碳原子沉积在催化剂表面，然后生长成所需的碳纳米结构。这一过程的关键可能与用于分解含碳气体的金属纳米催化剂的结构、形状、大小和化学和电子性质有关，以及其他因素，如压力和温度。虽然影响单壁碳纳米管选择性生长的一些工艺变量已经确定，但在大规模商业工艺开发之前，仍有许多悬而未决的问题。原子模拟将被用来阐明单壁碳纳米管生长过程的各个方面。理论模拟与实验研究完全结合在一起。理论研究将从生长过程的化学、热力学和动力学方面分析碳原子在金属纳米团簇上沉积的各个阶段。这些模拟研究将基于实验表面科学模拟的输入进行。该项目的智力优势集中在一种新方法的应用上，该方法有望有助于阐明单壁碳纳米管的生长机理，并有助于控制合成过程。拟议的研究包括一个重要的更广泛的影响，重点是将碳纳米管研究的两个经常分离的方面：理论和实验结合在一起的重要性。已经制定了一项同步计划，其中包括两所美国机构之间的教学、培训和学习方面，积极参与代表不足的少数族裔(如女性、西班牙裔和美洲原住民学生)，以及与其他卓越的学术和工业中心建立伙伴关系，以整合传统化学工程课程以外的研究。

Single-walled carbon nanotubes possess special chemical and electronic properties that make them extremely attractive for many applications in nanotechnology, biology, and medicine. These interesting properties are strongly dependent on the particular structure of the nanotubes. The goal of this research is to finely tune the synthesis process to produce only single-wall carbon nanotubes that have the desired diameter and chemical characteristics. A refined synthesis process that meets these goals has been developed, based on the flow of a carbon-containing gas over a dispersion of metal nanocatalysts. Such small metal particles catalyze the gas decomposition, yielding carbon atoms which are deposited over the catalyst surface and which then grow into the desired carbon nanostructures. The key to this processing may be related to the structure, shape, size, and chemical and electronic nature of the metal nanocatalysts used to decompose the carbon-containing gas, along with other factors such as pressure and temperature. Although some of these process variables affecting the selective growth of single-walled carbon nanotubes have been identified, many open questions still remain before a large-scale commercial process could be developed. Atomistic simulations will be used to elucidate aspects of the single-walled carbon nanotube growth process. The theoretical simulations are fully integrated with experimental investigations. Theoretical studies will analyze the various stages of deposition of carbon atoms on metallic nanoclusters with respect to the chemistry, thermodynamics, and kinetics of the growth process. These simulation studies will be carried out based on input from experimental surface science analogs. The intellectual merit of this project centers in the application of a novel approach which is expected to contribute to the elucidation of the single-wall carbon nanotubes growth mechanism and to the control of the synthesis process. The proposed research includes an important broader impact that focuses on the importance of bringing together two frequently separated aspects of carbon nanotube research: theory and experiments. A synchronized plan has been developed that includes aspects of teaching, training, and learning between two US institutions, active involvement of underrepresented minorities (such as female, Hispanic, and Native American students), and partnerships with other academic and industrial centers of excellence to integrate research beyond the traditional chemical engineering curriculum.