Solubilization of single-walled carbon nanotubes using Ozone generated by dielectric barrier discharge

This paper describes effects of ozone (O₃) concentration on water-solubility of single-walled carbon nanotubes (SWCNTs). Ozone was generated by dielectric barrier discharge (DBD) in atmospheric air with the maximum concentration of 220 ppm. Water solubility of ozone-treated SWCNTs, which was evaluated by optical absorbance of the SWCNT suspension, increased with ozone treatment time and reached the maximum in 60 min. The dispersed SWCNTs suspension was stable even after two months of the ozone treatment. Fourier transform infrared (FTIR) spectroscopy and Raman spectra analysis revealed that SWCNTs surface was functionalized with chemical group such as -COO^- after the ozone treatment. The longer ozone treatment introduced more functional groups and decreased zeta potential of the SWCNT surface, which improved watersolubility of the SWCNTs due to electrostatic repulsion force between them. It was also found that the ozone treatment induced morphological changes of SWCNTs.