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|Title:||Nanotube nucleation versus carbon-catalyst adhesion—probed by molecular dynamics simulations|
|Authors:||Ribas, Morgana A.|
Balbuena, Perla B.
Yakobson, Boris I.
Molecular dynamics method
|Publisher:||American Institute of Physics|
|Source:||Journal of chemical physics, 14 Dec. 2009, v. 131, no. 22, 224501, p. 1-7.|
|Abstract:||Catalytic nucleation of carbon nanotubes (CNTs) remains a challenge for the theory: Which factors and forces decide if the gathering sp²-network of atoms will adhere to the catalyst particle and fully cover it or the graphitic cap will liberate itself to extend into a hollow filament? This intimate mechanism cannot be seen in experiment, yet it can be investigated through comprehensive molecular dynamics. We systematically vary the adhesion strength (W[sub ad]) of the graphitic cap to the catalyst and temperature T (and C diffusion rate). Observations allow us to build a statistically representative map of CNT nucleation and define the conditions for growth or metal encapsulation in a fullerene-shell (catalyst poisoning). It shows clearly that weak W[sub ad], sufficient thermal kinetic energy (high T) or fast C diffusion favor the CNT nucleation. In particular, below 600 K carbon-diffusion on the catalyst surface limits the growth, but at higher T it fully depends on cap lift-off. Informed choice of parameters allowed us to obtain the longest simulated nanotube structures. The study reveals a means of designing the catalyst for better CNT synthesis, potentially at desirably low temperatures.|
|Rights:||© 2009 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in M. A. Ribas et al., J. Chem. Phys. 131, 224501 (2009) and may be found at http://link.aip.org/link/?jcp/131/224501.|
|Appears in Collections:||ITC Journal/Magazine Articles|
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