[2+1] Additions of (n,0)(n=6−10) single-walled carbon nanotubes with di-vacancies based on defect curvature: A first-principles study

Binding energies (E-b ), geometric and electronic structures for [2 + 1] (O/[2 1]) additions of O atom on (n, 0)(n = 6 - 10) single-walled carbon nanotubes with di-vacancies are studied using a GGA-PBE method, and defect curvature (KD-def ) is used to predict reactivities of different C-C bonds at defect area. Calculated results show that the C-C bonds can be divided into two types: broken C-C bonds corresponding to adducts with a C-O-C configuration structure and unbroken C-C bonds corresponding to adducts with a closed-3MR structure. E-b of O/[2 + 1] additions for the adduct with the C-O-C configuration structure monotonously increases with the increase of KD-def in any (n,0)(n = 6 - 10) tube and decreases with the increase of n in (n,0)(n = 6, 7, 10) tubes. Besides the fact that E-b value is mainly determined by the defect curvature, it is also affected by band gaps, bonding characteristic of C-C bonds in the highest occupied molecular orbital (HOMO) and geometric structures. The study would provide a theoretical basis for surface modifications of carbon nanotubes with atomic vacancy defects.