LIQUID PHASE FUNCTIONALIZATION OF CARBON NANOTUBES: MORPHOLOGY AND SURFACE MODIFICATION

Functionalization of carbon nanotubes was carried out at 333 K with a mixture of HNO3 (67 wt.%) and H2SO4 (98 wt.%). The influence of the nitric to sulphuric acid volume ratio on the morphology and crystalline quality of carbon nanotubes, as respectively monitored by transmission electron microscopy and Raman spectroscopy, was evaluated. The chemical composition of carbon surface upon different functionalization conditions, in terms of type and amount of oxygenated groups originated, was monitored by temperature pro- grammed desorption. The results showed that, as H2SO4 concentration increases, a strong enhancement of oxygenated groups occurs, while the tubular structure is preserved.