Oxidation using ozone in the presence of ultra-violet light was used to reduce the number of defects on carbon nanotubes. Fourier transform infra-red spectra showed that the treatment promoted milder oxidation in introducing carboxylic functional groups than did conventional acid treatments. Transmission electron microscope images suggested that ozone-treated carbon nanotubes suffered reduced attrition of broken tips, bent tips and bent walls in comparison to that of acid-treated carbon nanotubes. Raman spectra indicated that the acid-treated carbon nanotubes exhibited a lower IG:ID ratio than did ozone-treated carbon nanotubes; confirming that the former samples contained a higher number of defects. While the dispersion stability of the ozone treated carbon nanotubes was found at a level similar to that of acid-treated carbon nanotubes, the former showed a slightly larger amount of organic functional groups than the latter; as suggested by the thermal gravimetric analysis.

A Comparison of Defects Produced on Oxidation of Carbon Nanotubes by Acid and UV Ozone Treatment. A.B.Sulong, C.H.Azhari, R.Zulkifli, M.R.Othman, J.Park: European Journal of Scientific Research, 2009, 33[2], 295-304