Carbon Nanotube Synthesis by Open-Air Laser-Induced Chemical Vapor Deposition

提案题目：露天激光诱导化学气相沉积法合成碳纳米管碳纳米管具有显著的机械、电子和电化学性能，但只有优化和控制高数量和高质量的碳纳米管的生长才能充分发挥其应用潜力。本研究提出了一种新的合成技术，能够在露天（无反应器外壳）以非常高的沉积速率、最小的污染和低缺陷密度制造碳纳米管。露天特性允许连续沉积，这有利于扩大规模，并且具有通过选择性区域沉积和直接激光写入制造碳纳米管网络和图案的能力。然而，这种新工艺受到温度分布不均匀导致的不连续沉积、纳米管直径变化大以及缺乏控制纳米管质量所需知识的限制。该项目将为理解化学气相沉积（CVD）工艺提供必要的基础知识，并为实现该项目的长期目标提供必要的基础见解，该目标是控制工艺条件以获得所需质量的碳纳米管。在本研究中，我们将：(1)进行广泛的碳纳米管合成和表征实验，为模型开发和验证提供必要的化学动力学和纳米管结构信息；(2)建立能够预测生长过程中流体流动、传热传质的模型；(3)建立工艺参数与碳纳米管生长速率、性能和结构之间的关系。这个项目的发现可以直接应用于其他碳纳米管的合成方法。本研究的智力价值包括：(1)了解碳纳米管生长过程中沉积区域的传热传质以及由此产生的温度和化学物质；(2)激光与纳米催化剂的热输运、相互作用及沉积温度场；(3)结合实验数据的建模概念，在规定的加工参数下预测碳纳米管的结构和性能。知识的整合将使我们能够理解生长过程中复杂的传热传质过程，以及随后纳米管结构和性能的演变。这项研究的广泛影响包括独特的合作，以探索新的纳米技术应用于我们的社会。我们将与大学、工业和国家实验室合作，生产用于生物医学成像的高质量纳米管，并创造高表面积电极，以提高能量存储和能量转换设备的性能。在教育方面，每年将从当地高中挑选出几名优秀的高中生，特别是来自代表性不足的群体的学生，让他们到PI的实验室实习。从本研究中获得的知识将适用于CVD和CVD相关的碳纳米管合成方法。表征技术、软件工具和技术诀窍可以很容易地转移到工业、政府实验室和碳纳米管的其他用户。

NSF Proposal Number: CBET-0651687Principal Investigator: Wilson K. S. ChiuAffiliation: University of Connecticut Proposal Title: Carbon Nanotube Synthesis by Open-Air Laser-Induced Chemical Vapor DepositionCarbon nanotubes have remarkable mechanical, electronic and electrochemical properties, but the full potential for application will be realized only if the growth of high quantity and quality carbon nanotubes can be optimized and well controlled. This study proposes a new synthesis technique capable of creating carbon nanotubes in open air (no reactor enclosure) at very high deposition rates, minimal contamination, and low defect densities. The open-air feature allows for continuous deposition which is favorable for scale-up, and has the capability to make carbon nanotube networks and patterns by selective area deposition and direct laser writing. However, this new process is limited by non-uniform temperature distribution which causes discontinuous deposition, large nanotube diameter variation and the lack of knowledge necessary to control nanotube quality. This project will develop the fundamental knowledge necessary to understand this chemical vapor deposition (CVD) process and provide necessary fundamental insight to pursue this project's long term goals, which are to control process conditions to obtain carbon nanotubes of desired quality. In this study, we will: (1) Perform extensive carbon nanotube synthesis and characterization experiments to provide the chemical kinetics and nanotube structure information necessary for model development and validation; (2) Develop a model capable of predicting fluid flow, heat and mass transfer during growth; and (3) Establish relationships between process parameters and carbon nanotube growth rate, properties and structure. Findings from this project can be directly relevant and applicable to other carbon nanotube synthesis methods.Intellectual merit for this study include (1) understanding of heat and mass transfer and the resultant temperature and chemical species in the deposition region during carbon nanotube growth; (2) thermal transport and interaction of the laser beam with catalyst nanoparticles and the subsequent deposition temperature field; and (3) modeling concepts integrated with experimental data to predict carbon nanotube structure and properties at prescribed processing parameters. The integration of knowledge will allow us to understand the complex heat and mass transfer during growth, and the subsequent nanotube structure and properties that evolve.Broader impacts of this study include unique collaborations to explore new nanotechnology applications for our society. We will work with universities, industries and national labs to produce high quality nanotubes for biomedical imaging, and to create high surface area electrodes to enhance the performance of energy storage and energy conversion devices. In terms of education, several top high school students will be identified annually, especially from underrepresented groups, from local area high schools for internships in the PI's lab. Knowledge obtained from this study will be applicable to CVD and CVD-related carbon nanotube synthesis methods. Characterization techniques, software tools and technology know-how can be readily transferred to industry, government labs and other users of carbon nanotubes.