Band-gap sensitive adsorption of fluorine molecules on sidewalls of carbon nanotubes: an abinitio study

Abstract

We report from ab initio calculations that the band-gap sensitive side-wallfunctionalization of a carbon nanotube is feasible with the fluorine molecule(F2),which can provide a route to the extraction of semiconducting nanotubes by etching away metallicones. In the small diameter cases like (11, 0) and (12, 0), the nanotubes are easily functionalized withF2 regardless of their electronic properties. As the diameter becomes larger, however, thefluorination is favoured on metallic CNTs with smaller activation barriers than thoseof semiconducting ones. Our results suggest that low-temperature exposure toF2 molecules in the gas phase can make a dominant portion of fluorinated metallic nanotubesand unfluorinated semiconducting ones. This is consistent with recent experimentalreports.