A Novel High Yield Method for Dry Functionalization of Carbon Nanotubes

A novel and high yield (>80%) dry method to functionalize (dry functionalization) carbon nanotubes (CNTs) using hydrothermal method, is reported here. The hydrothermal solution was prepared with HNO₃, H₂SO₄ and H₂O₂ (1:3:2 vol. ratios) and reaction was carried out from 120 to 200 °C for 24 h. CNTs (multi wall) were kept in a way to avoid the direct contact with the solution. Treatment above 180 °C resulted in better functionalization of nanotubes as observed from Fourier transform infrared absorption spectroscopic (FTIR) measurements. Field emission scanning electron microscopic (FESEM) images showed that after functionalization, the nanotubes are seen with open ends, granular surface, twisted and are joined together. These clearly indicate the destruction of the graphite structure on the surface. This indicates that after treatment, CNTs reactivity has increased at the ends as well as at the side walls. X-ray Photoelectron Spectroscopic (XPS) studies show a shift in the C 1s peak position, increase in O 1s peak intensity and appearance of an N 1s peak.