  First-principles calculations reveal that the adsorption of representative
first-row atoms with different electronegativity, such as lithium (Li), carbon
(C) and fluorine (F), on zigzag single-walled boron nitride nanotubes (BNNTs)
exhibits surprising selectivity. The adsorption energy and adsorption site are
dependent upon the chemical activity of adsorbate with respect to the B and N
atoms in the host tube. In detail, the F atom prefers to be adsorbed on the top
of the B atom, the C atom is energetically favorable to stay on the bridge site
which is perpendicular to the tube-axis, and the Li atom hardly adheres to the
tube (an endothermal reaction). The adsorption behavior of these three types of
elements on BNNTs is elucidated based on the frontier molecular orbital theory.
In addition, the mechanism of modification of electronic structures of BNNTs by
adsorption is probed, and a feasible approach is proposed to tailor the
electronic properties of BNNTs.
