Biomedical Engineering Reference
In-Depth Information
parameters for an enhanced adsorption by nanotubes. So, in a
number of works is noted a positive influence of metal intercalation
(titanium [55, 56], palladium [57], and platinum) on the efficiency of
hydrogen adsorption by single-walled nanotubes. The combination
of the sorption properties of these metals with those of the carbon
nanotubes allowed to increase reliably the hydrogen sorption
capacity of such samples up to 8-12 wt%. Similar studies on metals
addition to adsorbent materials have been carried out also with
fullerenes [58, 59] and also in this case positive results have been
detected.
The synthesis of multi-purpose hybrid composite materials,
which combine fullerenes with attached photoactive ferrocenes
or porphyrins and single-walled carbon nanotubes in a single
multi-functional structure [60], can be considered as an obvious
continuation of the research line on creation of effective sorbents
by means of metals intercalation in carbon nanostructures. Such
combination makes this class of materials interesting for many
applications, including optoelectronics, photovoltaics, and even
biology.
Concluding this review it is interesting to note a further
research line, connected with the influence of electric potentials on
the hydrogen sorption efficiency of carbon-based adsorbents [61].
In this paper a marked increase in hydrogen adsorption has been
observed by applying 3 kV electric potential to activated carbon in
its pure form or in mixture with platinum.
Differences in the influence of the applied potential on the
adsorption have been observed to depend strongly on the gas
pressure above the adsorbent surface. For a mixture of activated
carbon and platinum, with applied 3 kV potential, at a pressure of
1.6 bar the sorption enhancement of hydrogen was of 625%, at the
pressure of 83 bars it was 30%. It is interesting to note that similar
effects on the adsorption enhancement, increasing the electric
potential up to 5 kV, have been observed also by the authors of the
this review for the oxygen sorption on fullerene samples [62]. At
the oxygen pressure of 0.2 bars and at 5 kV potential the sorption
enhancement reached about 150%. As it has been shown in Ref. [62],
such enhancement of the oxygen sorption by fullerene samples has
led, when irradiated, to the proportional increase of singlet oxygen
generation, an important result for practical applications.
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