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Thermal desorption of gases and solvents from graphite and carbon nanotube surfaces
CARBON, 44 (14): 2931-2942 (ноября 2006)
DOI: {10.1016/j.carbon.2006.05.040}
Аннотация
The interaction of 23 gases and solvents with the basal plane of highly
oriented pyrolytic graphite (HOPG) and with single-wall carbon nanotube
(SWCNT) samples is studied using thermal desorption spectroscopy.
Pre-exponential frequency factors used for analysis of desorption traces
are obtained from vapor pressure data. Activation energies for
desorption at monolayer coverage are determined using the Redhead
peak-maximum method. Binding energies of non-polar adsorbates to the
HOPG surface are found to scale with the adsorbate polarizability
providing clear evidence for the van der Waals character of the
interaction. Low coverage desorption temperatures on SWCNT samples are
found to be 50-100\% higher than on HOPG. Such increase has previously
been attributed to physisorption in higher coordinated sites such as
grooves on the external SWCNT rope surfaces. Polar adsorbates on the
other hand typically desorb at much higher temperatures from SWCNT
samples which is here tentatively attributed to stronger interaction
with defect sites. (c) 2006 Elsevier Ltd. All rights reserved.
