Dynamic observation of carbon nanotube growth on isolated catalyst nanoparticles

建议标题：碳纳米管在分离的催化剂纳米颗粒上生长的动态观察建议编号：CTS-0625340主要调查者：Renu Sharma研究所：亚利桑那州立大学分析(决定的基本原理)：该建议将研究一种两步法合成具有特定目标结构和性质的碳纳米管。这两个步骤都是独一无二的，将有助于更广泛的科学理解碳纳米管的合成。在第一步中，将使用电子束诱导沉积(EBid)纳米光刻方法原位制备定制催化剂。定制的eBid制造的催化剂，将颗粒小心地放置在二氧化硅薄膜中的孔的边缘，将允许畅通无阻地查看导致第二步中纳米管成核和生长的动态事件。通过乙炔在催化剂颗粒上的化学气相分解(CVD)，将观察到碳纳米管的原位成核和动态生长。这些研究将使用高分辨率(0.2 nm)受控环境(扫描)透射电子显微镜(ESTEM)。此外，还将获得纳米管和纳米颗粒亚纳米区域的纳米衍射数据，以及电子能量损失谱的成分和电子信息。考察了催化剂粒径、反应温度和压力对纳米管结构的影响。然后，将使用从头算方法对生长机制进行建模，并详细关注催化剂/纳米管的相互作用。还将对单个纳米管的拓扑结构及其缺陷结构进行建模。控制纳米管制造的能力将是朝着使用它们来构建电路或传感器板的更广泛目标迈出的重要一步。该项目开发的方法也可用于其他纳米级器件的设计。例如，电子束诱导沉积可以用来制造量子点阵列。本研究开发的组合催化表征技术也将有助于在典型反应温度下研究原子水平的催化，这可能对其他催化剂的设计具有指导意义。这些展示生长机制的视频与模型相结合，形成了对本科生纳米技术教育以及亚利桑那州立大学K-12推广计划的宝贵视觉教具。这位首席研究员一直是亚利桑那州立大学本科生项目中一个代表不足的群体中的成功科学家的榜样。

AbstractProposal Title: Dynamic Observation of Carbon Nanotube Growth on Isolated Catalysts Nanoparticles Proposal Number: CTS-0625340Principal Investigator: Renu SharmaInstitution: Arizona State UniversityAnalysis (rationale for decision):This proposal will investigate a two-step process to synthesize carbon nanotubes having specific targeted structures and properties. Both of these steps are unique and will contribute to a wider scientific understanding of carbon nanotube synthesis. In the first step, a custom catalyst will be prepared in situ using an electron beam induced deposition (EBID) nanolithographic method. The custom EBID-fabricated catalysts, with particles carefully placed at the edges of holes in a SiO2 film, will allow unobstructed views of the dynamical events leading to nucleation and growth of nanotubes during the second step. The in situ nucleation and dynamic growth of carbon nanotubes via chemical vapor decomposition (CVD) of acetylene over the catalyst particles will be observed. A high-resolution ( 0.2 nm) controlled environment (scanning) transmission electron microscope (ESTEM) will be used for these studies. In addition nanodiffraction data from sub-nanometer regions of the nanotubes and particles will be obtained, as well as compositional and electronic information by electron energy loss spectroscopy. The effect of catalyst particle size and reaction temperature and pressure on nanotube structure will be determined. Growth mechanisms will then be modeled using ab initio methods, with detailed attention paid to the catalyst/nanotube interactions. The topologies of individual nanotubes and their defect structures will also be modeled.The ability to control the fabrication of nanotubes will be an important step towards the broader goal of using them to building circuits or sensor boards. The methods developed in this project can also be used for designing other nanoscale devices. For example, electron beam induced depositions can be used to fabricate arrays of quantum dots. Combinatorial catalysis characterization techniques developed in this research will also be useful for studying catalysis at the atomic level at typical reaction temperatures, with possible implications for the design of other catalysts. The videos showing growth mechanisms, combined with models, form invaluable visual aids for undergraduate nanotechnology education as well as for the Arizona State K-12 outreach program. The principal investigator has been a role model as a successful scientist from an underrepresented group for the undergraduate program at ASU.