Influence of helium, hydrogen, oxygen, air and methane on conductivity of multiwalled carbon nanotubes

Temperature dependences of the conductivity of catalytic multiwalled carbon nanotubes (MWNTs) were measured in various gas environments: helium, hydrogen, oxygen, air and methane. We had found that in the vicinity of the melting and vaporization temperatures of hydrogen, oxygen, air and methane the conductivity sharply decreases by (2–12%). The observed reversible change of the conductivity is connected with the adsorption–desorption of gases on the surface of nanotubes and breakup-recovery of contacts between nanotubes as a result of melting and vaporization of hydrogen, oxygen, air and methane.