A reasonable criterion of nitrogen-doped single-walled carbon nanotubes with pyridine-like configurations

Bond curvature K-D as a universal criterion is used to identify structures and reactivities of N-2-doped single-walled carbon nanotubes. Calculations of adjacent N-2-dopings show that, as K-D is large, a pyridine-like structure is formed and the formation energies E-f linearly decrease with increasing K-D, whereas as K-D is small, the doping N-N bond cannot be broken. A boundary of K-D between generating broken and unbroken N-N bond structures is about 1.6 nm(-1). For the (n,0) tubes, the E-f of products with the pyridine-like configurations have an odd-even oscillation rule with n values, and display a decreasing trend with increasing K-D. As the largest value K-largest among all K-D in a given tube is small, two N atoms are inclined to disperse in the tube and its product has a perfect sp(2) hexagonal network configuration. The approximate border value of K-largest for the adjacent and disperse substitutions is 2.3 nm(-1). Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.