First-Principles Study of the Oxygenation of Carbon Nanotubes and Boron Nitride Nanotubes

Using the first-principles method, we investigated the molecular and electronic structures of oxygenized carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs). This is done by considering (5,5) and (10,0) tubes, which have similar diameters. The reaction of CNTs with oxygen molecules is largely exothermic, particularly for (5,5) CNT. When the oxygen content is ∼5% in a (5,5) tube, oxygen atoms tend to form a contiguous row of ether along the tube axis, which can be understood in terms of a zipping mechanism. In (10,0) CNT, oxygen atoms tend to be uniformly distributed in pairs of ether on two opposite sides of the tube up to 10% oxygen content. Upon acid treatment of BNNTs, our data indicate that the oxygenation could occur in a chirality-specific way. Specifically, (5,5) BNNT is expected to favor the insertion of two oxygen atoms in the tube rather than the evaporation of an oxygen molecule, whereas (10,0) BNNT is not expected to do so.