Effects of vacancy-carboxyl pair functionalization on electronic properties of carbon nanotubes

Density functional calculations are performed to investigate the functionalization of carbon nanotubes with the vacancy and carboxyl group that always appear in pairs after chemical oxidation (such as oxidative acid treatment). It is found that the geometrical structures and electronic properties of the nanotubes are changed significantly, with the formation of a strong covalent bond between the carboxyl and the defected 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, is designed to make carbon nanotube-based chemical and nanoelectronic devices. (c) 2006 American Institute of Physics.