Stone-wales defects in single-walled boron nitride nanotubes: Formation energies, electronic structures, and reactivity

The geometries, formation energies, electronic properties, and reactivities of Stone-Wales (SW) defects in single-walled (8,0) boron nitride nanotubes (BNNTs) were investigated by means of gradient-corrected density functional theory (DFT) computations. SW defects deform BNNTs severely and result in local curvature changes at defect sites. The energies of defect formation increase with increasing tube diameters and are orientation dependent. Depending on the SW defect orientations, additions to central 7-7 ring fusions can be either more or less favorable than to defect-free sites. The reaction energies of model H-2 addition are mostly endothermic for defective as well as pristine BNNTs, but reactions at the most favorable sites near SW defect (homoelement N-N bonds followed by the B-B bond sites) are exothermic. This and the fact that the band structures of BNNTs are only slightly changed by SW and vacancy defects as well as by chemical additions at low modification ratios endow BNNTs with great application potential.