Multi-walled carbon nanotubes experiencing electrical breakdown as gas sensors

This paper presents a new approach to gas sensing using a multi-walled carbon nanotube (MWCNT) subject to electrical breakdown. The electrical resistances of large-diameter MWCNTs were found to decrease in the presence of air after experiencing electrical breakdown, while pristine MWCNTs were not appreciably sensitive. The sensitivity could be controlled by manipulating the level of the electrical breakdown, and larger-diameter MWCNTs showed better sensitivity because they possess more damaged shells that can create more adsorption sites for oxygen molecules. It was suggested by theoretical calculations that the oxygen sensitivity might be associated with an oxidized junction that exists between the outer and inner shells of the nanotubes.