Experimental/ ab initio calculations; carbon nanotubes; diffusion; molecular dynamics method/ ab initio molecular dynamics simulations; single-walled carbon nanotube; metal nanoparticles; sp 2 bonded cap; iron catalyst; hydrocarbon precursors; weak adhesion; graphene sheet; total energy calculations; early growth stages; C; Fe/ A8120V Preparation of fullerenes and fullerene-related materials, intercalation compounds, and diamond A6148 Structure of fullerenes and fullerene-related materials/ C/el; Fe/el
Abstract :
[en] We report on ab initio molecular dynamics simulations of the early stages of single-walled carbon nanotube (SWCNT) growth on metal nanoparticles. Our results show that a sp2 bonded cap is formed on an iron catalyst, following the diffusion of C atoms from hydrocarbon precursors on the nanoparticle surface. The weak adhesion between the cap and iron enables the graphene sheet to "float" on the curved surface, as additional C atoms covalently bonded to the catalyst "hold" the tube walls. Hence the SWCNT grows capped. At the nanoscale, we did not observe any tendency of C atoms to penetrate inside the catalyst, consistent with total energy calculations showing that alloying of Fe and C is very unlikely for 1 nm particles. Root growth was observed on Fe but not on Au, consistent with experiment
Disciplines :
Physics
Author, co-author :
Raty, Jean-Yves ; Université de Liège - ULiège > Département de physique > Physique de la matière condensée
Gygi, F.
Galli, G.
Language :
English
Title :
Growth of carbon nanotubes on metal nanoparticles: a microscopic mechanism from ab initio molecular dynamics simulations
Publication date :
2005
Journal title :
Physical Review Letters
ISSN :
0031-9007
eISSN :
1079-7114
Publisher :
American Physical Society, Ridge, United States - New York
F. Ding, A. Rosen, and K. Bolton, J. Chem. Phys. 121, 2775 (2004); JCPSA6 0021-9606 10.1063/1.1770424
O. Louchev, H. Kanda, A. Rosen, and K. Bolton, J. Chem. Phys. JCPSA6 0021-9606 121, 446 (2004); 10.1063/1.1755662
F. Ding, A. Rosen, and K. Bolton, Chem. Phys. Lett. 393, 309 (2004). CHPLBC 0009-2614 10.1016/j.cplett.2004.06.056
Y. Shibuta and S. Maruyama, Chem. Phys. Lett. 382, 381 (2003). CHPLBC 0009-2614 10.1016/j.cplett.2003.10.080
R. Car and M. Parrinello, Phys. Rev. Lett. 55, 2471 (1985). PRLTAO 0031-9007 10.1103/PhysRevLett.55.2471
We use a plane-wave basis with Ecut=35Ry and Hamann-type pseudopotentials. Iron d and s electrons were included in the valence, and core electrons were treated using semilocal pseudopotentials. Exchange and correlation energy was treated in the generalized gradient approximation. Comparison with calculations including spin and a higher Ecut(=50Ry) for model systems (see text) have been performed to ensure convergence in total energy differences. The temperature of the simulation was controlled via a velocity rescaling thermostat and set to 1200 K to correspond to the experimental condition of Ref. The electrons were kept at 0K. Simulations were carried out with the GP code (F. Gygi, LLNL).
D. Hash, D. Bose, T.R. Govindan, and M. Meyyappan, J. Appl. Phys. 93, 6284 (2003), and references therein. JAPIAU 0021-8979 10.1063/1.1568155
See EPAPS Document No. E-PRLTAO-95-042535 for the molecular dynamics simulation animated sequences. This document can be reached via a direct link in the online article's HTML reference section or via the EPAPS homepage (http://www.aip.org/pubservs/epaps.html).
