Chemical modification of multiwalled carbon nanotubes by vacuum ultraviolet irradiation dry process

We developed a fast dry oxidation process for chemical vapor deposition (CVD) grown multiwalled carbon nanotubes (MWNTs) using short-wavelength UV [vacuum ultraviolet (VUV) light (λmax=172 nm)] irradiation. We introduced carboxyl groups as many as 3% of carbon atoms within 1 min at room temperature using this process. MWNTs with the carboxyl groups were analyzed by attenuated total reflection (ATR) Fourier transform infrared absorption spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The attachment of the carboxyl groups was further confirmed by reacting ferritin molecules with the MWNTs. The developed dry process with a high reaction rate is a powerful tool for the applications of carbon nanotubes in nanoelectronics.