Computational Study of Catalyst Nanoparticles for Growth of Single-Walled Carbon Nanotubes

Speaker: 
Neha Awasthi
Date of Seminar: 
Fri, 2007-11-02 12:00
Semester & Year: 
Fall 2007
Seminar Location: 
Hudson Hall Room 216
Seminar Contact(s): 
Elizabeth Irish eri@duke.edu or Justin Jaworski jwj@duke.edu
Special Instructions: 
Lunch and beverages will be served
Due to their unique structures and chiralities, Single Walled Carbon Nanotubes (SWCNTs) show excellent electronic transport properties, high mechanical flexibility, and chemical stability. Based on these properties, SWCNTs have potential applications in electrically conducting plastics, transparent electrodes, flexible transistors and field emission displays. Among the established methods for single-walled carbon nanotubes (SWCNTs) synthesis, the low temperature Catalytic Chemical Vapor Decomposition (CCVD) technique is more appropriate for growing nanotubes on a substrate at a target position and, thereby, can accelerate the integration of this unique material in hybrid electronics. Catalyst nanoparticles such as Fe, Mo, Ni, and Co play a crucial role in nanotube synthesis in CCVD reactions. Extensive research is being done in understanding the catalytic growth mechanism in order to identify the optimal catalyst and ideal growth conditions for selective and economical large scale production of SWCNTs. In my talk, I will present results from ab-initio (density functional theory) and classical molecular dynamics simulations performed for Fe and Fe:Mo catalysts in order to: 1) Understand the influence of alumina substrate on the catalytic activity of Fe nanoparticles. 2) Investigate the melting of free and alumina-supported Fe-C nanoparticles to develop Fe-C phase diagrams. 3) Explore the structural peculiarities of extremely small nanoparticles. 4) Understand the solubility of C in Fe nanoparticles, formation of carbides (Fe3C) and its implications on the catalytic activity of Fe. 5) Explain the mechanism for enhanced catalytic activity of binary Fe:Mo catalyst over pure Fe catalysts.