Zig-zag boron nitride nanotubes functionalization with acetylene molecules: a density functional theory study

Spin-polarized first-principles total-energy calculations have been performed in order to investigate the organic functionalization of zig-zag boron nitride nanotubes (BNNTs) with acetylene molecules. Calculations have been done within the periodic density functional theory (DFT), including van der Waals interactions. We have considered zig-zag (n, 0) BNNTs with n = 5, 10 and 15. Nanotubes with no defects exhibit weak interactions with the acetylene molecules. Therefore, we have generated boron and nitrogen vacancy-type defects to favor the adsorption. Results show that chemisorption occurs in all cases with adsorption energies in the range of − 3.6 eV to − 5.3 eV, with adsorption in nanotube (5, 0) and (10, 0) being the most and least favorable, respectively. We find that nanotubes with boron vacancies show a stronger interaction than the nanotubes with nitrogen vacancies. Minimum energy pathways show that activation energies are of the order of 0.1–1.6 eV, with the lowest energy barrier for the nanotubes with nitrogen vacancies. Analysis of the density of states (DOS) show that the organic molecule modifies the electronic structure.