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

University Of Connecticut, Storrs CT

Investigators

Abstract

NSF Proposal Number: CBET-0651687 Principal Investigator: Wilson K. S. Chiu Affiliation: University of Connecticut Proposal Title: Carbon Nanotube Synthesis by Open-Air Laser-Induced Chemical Vapor Deposition Carbon 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.