Due to their cylindrical geometry and their nanometric scale
Due to their cylindrical
geometry and their nanometric scale, CNTs are candidates
for potential applications like hydrogen storage 6–9.
However, the amount of hydrogen stored in CNTs is below
the DOE 2015 requirements (9 wt.%) 10. Nevertheless, hydrogen
storage properties of nanotubes are not yet fully understood
and explored. Careful investigations are needed to
improve the sorption behaviors 11.
Single wall carbon nanotubes (SWNTs) with their welldefined
atomic structure, their high length to diameter ratio,
and their chemical stability constitute one-dimension
molecules 12. SWNTs exhibit specific electronic properties
and can be either metallic or semiconducting depending
on their geometry.
Production of carbon nanotubes in a controlled way and
in large amount encounters problems, which remains to be
solved. It is needed to identify all properties of these tubes.
However, to fully characterize carbon nanotubes, there are
not so many techniques available. The aim of this paper is
about the characterization methods of the CNTs. Structure of
CNTs are first summarized. Then, morphological and structural
characterization methods are reviewed. The particular
behavior of nanotubes with very small diameter and the separating
methods of the semiconducting/metallic tubes are also
approached before concluding this paper.