Julian Gale, Professor of Computational Chemistry at Curtin University of Technology in Perth, Australia will present the following seminar from the Pacific Rim Conference in Nanoscience (7-11 September 2004). The seminar will be available for viewing and discussion through the Nanotech Hub at http://nanotech.colayer.net/
Hydrogen storage in nanotubes – has it all gone pear-shaped?: A computational perspective
Hydrogen has been proposed as the clean energy source of the future, since the combustion product is only water. However, this requires both the efficient generation of hydrogen and an effective means of transportation. There has been considerable interest in the possibility of employing carbon nanotubes for hydrogen storage, as an alternative to compression or metal hydrides.
While it is likely that the majority of hydrogen will be physisorbed, either within the nanotubes, or in the space between them, there is also the possibility that some hydrogen may be chemisorbed. The thermodynamics of the reactivity of carbon nanotubes with respect to this process has been investigated using non-local density functional theory, as implemented within the SIESTA approach [1]. The variation with respect to the radius of a one-dimensional infinite nanotube has been examined, as well as the trend with successive hydrogenations. In addition, the influence of the termination of the nanotube has been investigated. Chemisorption is found to strongly perturb the shape of nanotubes, which will have important consequences for their physisorption capacity and other properties.
In order to extend the configuration space accessible, the reactivity of nanotubes with respect to hydrogen has been further explored through the use of bond-order potentials of the form proposed by Brenner et al [2], as implemented within the program GULP3 [3]. Through this approach, a preliminary evaluation of the kinetics of the process has also been made. Finally, the influence of doping of the nanotube has been considered to see if it would assist in improving the characteristics of such materials for hydrogen storage.
References:
[1] J.M. Soler, E. Artacho, J.D. Gale, A. Garcia, J. Junquera, P. Ordejon, D. Sanchez-Portal, J. Phys.: Condens. Matter , 14 , 2745 (2002)
[2] D.W. Brenner, O.A. Shenderova, J.A. Harrison, S.J. Stuart, B. Ni, and S.B. Sinnott, J. Phys.: Condens. Matter , 14 , 783 (2002)
[3] J.D. Gale and A.L. Rohl, Mol. Simul. 29 , 291 (2003)
Barry Hardy
Douglas Connect
www.douglasconnect.com
Nanotechnology Hub: http://nanotech.colayer.net/
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