Theoretical investigation of the divacancies in boron nitride nanotubes: Properties and surface reactivity toward various adsorbates

The recent study has shown that the point defects formed under electron irradiation in the boron nitride nanotubes (BNNTs) are primarily BN divacancies. In the present work, we explore the properties of BNNTs with divacancies and estimate their surface reactivity toward various adsorbates through density functional theory calculations. Divacancies in BNNTs can self-heal by spontaneously reconstructing stable structures that have two pentagons side by side with an octagon (585). The formation energies, which strongly depend on the divacancy orientation with respect to the tube axis, increase with increasing tube diameters. Compared to the reactivity of the perfect BNNT, those sites near the divacancies have a higher reactivity due to the formation of frustrated B–B and N–N bonds and the local strain induced by pentagonal and octagonal rings. The present results might be useful for deeply understanding the nature of defects in BNNTs and rendering BNNTs promising for many applications, especially in nanoelec...