Single-walled carbon nanotube networks for ethanol vapor sensing applications

Networks of pristine high quality single walled carbon nanotubes (SWNTs), the
SWNTs after Ar-plasma treatment (from 2 to 12 min) and carbon nanobuds
(CNBs) have been tested for ethanol vapor sensing. It was found that the
pristine high quality SWNTs do not exhibit any ethanol sensitivity, while the
introduction of defects in the tubes results in the appearance of the ethanol
sensitivity. The CNB network showed ethanol sensitivity without plasma
treatment. Both CNB and low defect (after 3 min treatment) SWNT networks
exhibit significant drift in the resistance baseline, while heavily plasma-treated
(9 min) SWNTs exhibited high ethanol vapor sensitivity without the baseline
change. The mechanisms of the ethanol sensitivity and stability after the plasma
irradiation are attributed to the formation of sensitive dangling bonds in the
SWNTs and formation of defect channels facilitating access of the ethanol vapor
to all parts of the bundled nanotubes.