Work function of (8,0) single-walled boron nitride nanotube at the open tube end

Abstract

The effects of hydrogen (H) and fluorine (F) chemisorption on the work function (Φ) and polarization field of (8,0) boron nitride nanotubes (BNNT) have been investigated using periodic density functional theory. The binding energies of coadsorbed H and F atoms on B and N sites in BNNT are much higher than that of single adsorption case. The work function at the open tube end can be affected by adsorption on the tube wall due to changes in the macroscopic polarization field along the tube, as well as the shifting of the Fermi level. Among the various adsorption patterns on the wall, we found that adsorption of H,F pairs, or H,H pairs, on the tube wall to form a continuous, armchair chain along the tube axis, produces strong enhancement of the intrinsic polarization field. With wall adsorption of (H,H) pairs, the Φ at the B terminal becomes 3.25eV, compared with 5.40eV of the pristine tube, and with (H,F) pairs wall adsorption, the Φ at the B terminal is reduced to 3.56eV.