Biomedical Engineering Reference
In-Depth Information
In particular during the period 1997-2005, new 1D carbon
nanomaterials, such as single-wall and multiwall carbon nanotubes
and graphite nanofibers (GNFs) (Figs. 2.1 and 2.2), were considered
promising sorbents of hydrogen for automobile fuel cells by many
researchers and were intensively studied (see the reviews in Refs.
[4-11]). During this period, investigations were carried out on
the crucial and yet open questions about nature, mechanisms,
and ultimate storage capacity of hydrogen sorption by carbon
nanostructures (single-wall nanotubes, multiwall nanotubes, GNFs,
etc.), and about the prospects of effectively using such nanostructures
as storage material for the hydrogen power industry.
The reviews in Ref. [8-11] show that numerous experimental
data obtained in various laboratories in the period 1997-2002
(Figs. 2.3 and 2.4) and 2002-2005 on the hydrogen sorption capacity
by the new carbon nanomaterials, have a spread of about three
orders of magnitude, that the most interesting experimental results
are not reproducible in other laboratories, and that no experimental
explanation or justification of such circumstance exists.
Figure 2.2
Hydrogen sorption by a homotype bundle of single-wall
nanotubes:
(1) inside nanotubes, theoretical value of the
binding energy (physical adsorption) -0.062 eV (−6.0 kJ mol
-1
(H)
in channels between nanotubes -0.119 eV (−11.5
kJ mol
−1
(H
);
(2)
2
);
(3) in surface grooves -0.089 eV (−8.6 kJ mol
−1
2
(H
));
(4)
on the outer surface of the bundle −0.049 eV (−4.7
2
kJ mol
−1
(H
)).
2
