(45g) Combined Effect of Catalyst Size and Metal-Carbon Interactions On the Growth of Single Wall Carbon Nanotubes

Reactive molecular dynamics simulations are carried out with the purpose of analyzing how the catalyst particle size and the strength of adhesion between the catalyst surface and carbon structures formed at initial stages may affect the growth process of single wall carbon nanotubes (SWCNT), leading to cap lift-off or otherwise causing graphitic encapsulation and therefore poisoning of the catalyst. Our MD simulations show that the size of the particle defines the diameter of the resulting fullerene and therefore its curvature energy. We found that the work of adhesion must be weak enough to avoid the curvature energy of a spherical fullerene to be favorable over that of a single-wall carbon nanotube of the same diameter allowing in this way the lifting of caps, these results were found in agreement with the Smalley-Hafner curvature energy model1. Moreover, we propose that a simple model combining thermodynamic and kinetic effects may help to identify regions of single-wall carbon nanotube growth in the phase space defined by work of adhesion, temperature, and catalyst size.

Reference (1) Hafner, J. H.; Bronikowski, M. J.; Azamian, B. R.; Nikolaev, P.; Rinzler, A. G.; Colbert, D. T.; Smith, K. A.; Smalley, R. E. Chemical Physics Letters 1998, 296, 195.