Carbon-alloying of the rear surfaces of nanotubes by direct fluorination Original Research Article

Carbon nanotubes prepared by pyrolytic carbon deposition onto anodic aluminum oxide films were fluorinated in the temperature range from 50 to 200°C. X-ray photoelectron spectroscopy (XPS) was used to investigate changes in the chemical nature of their surface. Fluorine atoms are covalently bonded to carbon atoms on the internal surfaces (rear surfaces) of the tubes. The amount of fluorine attached on the tubes increases with increasing reaction temperature. The Raman spectra show a pair of bands at 1340 and 1590 cm−1 peculiar to disordered sp2-carbons. The transmission electron microscope (TEM) bright-field images of the products were similar to those of pristine tubes. These results indicate that C–F bonds are formed on the rear surfaces of the tubes, viz. carbon-alloying via fluorination, while the external surfaces as well as the layers between the internal and external surfaces retain their sp2-hybridization.