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.
