BASIC CONCEPTS AND AN OVERVIEW - Foundations of Nanotechnology: Pore Size in Carbon-Based Nano-Adsorbents - page 46

and the carbon nanofibers known from catalysis are relatives and this broadens
the scope of knowledge and of applications. It has been realized, however, that
arc-discharge and laser-ablation methods lead to mixtures of carbon materials and
thus to a cumbersome purification to obtain nanofibers or nanotubes [88].
From an application point of view, Some of best application of carbon nano
fibers include: Carbon nanofibers as catalyst support materials, Carbon nanofiber
based electrochemical biosensors,CNF-based oxidase biosensors, CNF-based im-
mune sensor and cell sensor and hydrogen storage. The overall economics are
affected by the fiber yield, the feedstock used, the rate of growth, and the reactor
technology [88-92].The growth of parallel fibers using iron as the catalyst has
been studied in detail by high-resolution transmission electron microscopy (HR-
TEM). It is noted that the graphite layers grow at an angle iron surface, thus lead-
ing to parallel fibers. The diameter of the fibers can be varied by variation of the
metal particle size. If we want to vary the fiber diameter for a macroscopic sample,
however, we need a narrow metal particle size distribution. In general, one can say
that the fibers do not contain micropores and that the surface area can range from
10 to 200 m 2 /g and the mesopore volume ranges between 0.50 and 2.0 mL/g. Note
that these pore-volume data are obtained htiw fibers as grown, specific treatments
in the liquid phase can be applied to largely reduce the pore volume and to obtain
much denser and compact fiber structures. Compared to the large volume of lit-
erature on the mechanism of growth, the studies on the macroscopic, mechanical
properties of bodies consisting of agglomerates of carbon nanofibers have been
limited in number. Give a useful description of the tertiary structures that can be
obtained; that is, “bird nests,”“neponet,” and “combedyarn.” In general, porous
bodies of carbon nanofibers are grown from porous supported metal catalyst bod-
ies. Some others in the size range of micrometer to millimeter. As carbon precur-
sors, PAN and pitches were frequently used, probably because both of them are
also used in the production of commercial carbon fibers. In addition, poly(vinyl
alcohol) (PVA), polyimides (PIs), polybenzimidazol (PBI) poly(vinylidene fluo-
ride) (PVDF), phenolic resin and lignin were used. In order to convert electrospun
polymer nanofibers to carbon nanofibers, carbonization process at around 1000°C
has to be applied. In principle, any polymer with a carbon backbone can poten-
tially be used as a precursor. For the carbon precursors, such as PAN and pitches,
so-called stabilization process before carbonization is essential to keep fibrous
morphology, of which the fundamental reaction is oxidation to change resultant
carbons difficult to be graphitized at high temperatures as 2500°C [89, 90].
Carbon is an important support material in heterogeneous catalysis, in par-
ticular for liquid-phase catalysis. A metal support interaction between Ru and C
was suggested as a possible explanation for these very interesting observations.
More recent work focuses on the use of platelet type fibers exposing exclusively
graphite edge sites. Using a phosphorus-based treatment, preferential blocking
of so-called armchair faces occurs. Deposition of nickel onto the thus modified