LAUSR

A carbon nanocondensate containing multiwalled carbon nanotubes has been produced by dissociation of CO molecules on an iron-nickel catalyst at temperatures of 400–500 °C. X-ray diffraction is used to show that this condensate contains two phases with different densities and degrees of ordering. Elevated synthesis temperatures lead to a higher density and smaller differences in the phases, which are related to increased freedom from defects in the carbon layers and a greater number of layers in the multiwalled carbon nanotubes. Studies of the sorption and subsequent desorption kinetics of hydrogen by the synthesized samples at temperatures of 7–120 K showed that when the temperature is lowered from 120 to 65 K, an increased sorption time for H2, which is typical of thermally activated diffusion, was observed in all the samples. At temperatures below 65 K the characteristic hydrogen sorption times depended weakly on temperature; this can be explained by a predominance of tunnel diffusion over thermally act...