The influence of treatment duration on multi-walled carbon nanotubes functionalized by H2SO4/HNO3 oxidation

▶ Decrease in crystallinity was from widening of XRD peak, followed by shifting towards lower angles. ▶ A defect peak in XPS C1s spectra was helpful for detecting the generation of defect sites. ▶ The oxidation mechanism of MWCNTs in mild H2SO4/HNO3 mixture was proposed.