Electronic properties of carbon nanotubes partially unzipped by oxygenation or fluorination

Unzipping carbon nanotubes has recently attracted interest as a promising route to synthesizing semiconducting graphene nanoribbons. Here, the band structures of O- and F-driven partially unzipped armchair carbon nanotubes (PUCNTs) are computed using the ab initio pseudopotential method. Although the model structures exhibit a similar pinhole with a length of ∼ 1 nm along the tube axis, the band structures differ distinctly. The O-driven PUCNT has many localized states in the valence band arising mainly from the O 2p orbitals, and preserves metallic properties. In contrast, the F-driven PUCNT shows properties of a semiconductor with a bandgap of ∼ 0.15 eV , and its localized states occur in the conduction band. When the unzipping process continues further, the O-driven PUCNT also shows the semiconducting behavior.