posted on 2014-11-07, 00:00authored byEvgeniy O. Pentsak, Evgeniy
G. Gordeev, Valentine P. Ananikov
Microwave
irradiation of Ni, Co, Cu, Ag, and Pt metal salts supported on graphite
and charcoal revealed a series of carbon surface modification processes
that varied depending on the conditions used (inert atmosphere, vacuum,
or air) and the nature of metal salt. Carbon materials, routinely
used to prepare supported metal catalysts and traditionally considered
to be innocent on this stage, were found to actively change under
the studied conditions: etching and pitting of the carbon surface
by metal particles as well as growth of carbon nanotubes were experimentally
observed by FE-SEM analysis. Catalyst preparation under microwave
irradiation led to the formation of complex metal/carbon structures
with significant changes in carbon morphology. These findings are
of great value in developing an understanding of how M/C catalysts
form and evolve and will help to design a new generation of efficient
and stable catalysts. The energy surfaces of carbon support modification
processes were studied with theoretical calculations at the density
functional level. The energy surface of the multistage process of
carbon nanotube formation from an etched graphene sheet was calculated
for various types of carbon centers. These calculations indicated
that interconversion of graphene layers and single wall carbon nanotubes
is possible when cycloparaphenylene rings act as building units.