Density functional calculations were used to investigate the functionalization of C nanotubes with the vacancy and carboxyl group that always appeared in pairs after chemical oxidation (such as oxidative acid treatment). It was found that the geometrical structures and electronic properties of the nanotubes were changed significantly, with the formation of a strong covalent bond between the carboxyl and the defective tube. The electrical conductivity of the system could be considerably enhanced, which sensitively depends upon the axial density of vacancy-carboxyl pairs. A promising approach, controllable oxidative acid treatment, was designed to make C nanotube-based chemical and nano-electronic devices.

Effects of Vacancy-Carboxyl Pair Functionalization on Electronic Properties of Carbon Nanotubes. C.Wang, G.Zhou, J.Wu, B.L.Gu, W.Duan: Applied Physics Letters, 2006, 89[17], 173130 (3pp)