27 research outputs found
Uptake of gases in bundles of carbon nanotubes
Model calculations are presented which predict whether or not an arbitrary
gas experiences significant absorption within carbon nanotubes and/or bundles
of nanotubes. The potentials used in these calculations assume a conventional
form, based on a sum of two-body interactions with individual carbon atoms; the
latter employ energy and distance parameters which are derived from empirical
combining rules. The results confirm intuitive expectation that small atoms and
molecules are absorbed within both the interstitial channels and the tubes,
while large atoms and molecules are absorbed almost exclusively within the
tubes.Comment: 9 pages, 12 figures, submitted to PRB Newer version (8MAR2K). There
was an error in the old one (23JAN2K). Please download thi
Critical size and surface effect of the hydrogen interaction of palladium clusters
Metal hydrides are used for electrochemical or gaseous storage of hydrogen because considerable amounts of
hydrogen are reversibly absorbed and desorbed at interstitial sites. Palladium is often used as a model system.
Nanophase material is of interest because properties related to the hydrogen absorption are size dependent. In
this study, clusters from the size of 55 to 1415 atoms are investigated and compared with bulk Pd. It turns out
that not only the amount of hydrogen per palladium that can be intercalated changes but also kinetics and
chemical potentials are dependent on the cluster size. The clusters used for this study were chemically
synthesised and stabilised by a ligand shell
Nanostructured graphite-hydrogen system prepared by mechanical milling under hydrogen and argon atmospheres
Density and thermodynamics of hydrogen adsorbed on the surface of single-walled carbon nanotubes
Preparation and electrochemical hydrogen storage of boron nitride nanotubes
Boron nitride (BN) nanotubes were synthesized through chemical vapor deposition over a wafer made by a LaNi5/B mixture and nickel powder at 1473 K. Scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were performed to characterize the microstructure and composition of BN nanotubes. It was found that the obtained BN nanotubes were straight with a diameter of 30-50 nm and a length of up to several microns. We first verify that the BN nanotubes can storage hydrogen by means of an electrochemical method, though its capacity is low at present. The hydrogen desorption of nonelectrochemical recombination in cyclic voltammograms, which is considered as the slow reaction at BN nanotubes, suggests the possible existence of strong chemisorption of hydrogen, and it may lead to the lower discharge capacity of BN nanotubes. It is tentatively concluded that the improvement of the electrocatalytic activity by surface modification with metal or alloy would enhance the electrochemical hydrogen storage capacity of BN nanotubes