Aluminum doping makes boron nitride nanotubes (BNNTs) an attractive adsorbent of hydrazine (N2H4)

Abstract

Adsorption of toxic hydrazine (N2H4) at the surface of pristine and Al-doped single-wall boron nitride nanotubes (BNNTs and Al-BNNTs) has been investigated using density functional theory (DFT). Single hydrazine molecule was allowed to interact with Lewis acid center (i.e., B atom) of BNNTs, where most stable gauche conformer of the guest is used. Both zigzag (8,0) and armchair (4,4) variants of BNNTs were considered and to estimate the effect of tube diameter on adsorption energies wider zigzag (9,0) and (10,0), and armchair (5,5) and (6,6), tubes were included in the host list. Estimated adsorption energies of 2–8 kcal/mol do not support strong binding between pristine BNNTs with hydrazine. However, Al doping makes BNNTs an attractive adsorbent of N2H4 with adsorption energy in the range of 32–35 kcal/mol. Stability of such complexes is found less sensitive to the chirality, but nominally decreases with tube diameter. Thus, a large quantity of hydrazine may be adsorbed by Al-BNNT samples. The dative N: → B/Al bond between hydrazine and host tubes is the source of stability of complexes. Molecular electrostatic potentials (MEPs) and frontier molecular orbitals of host and guest were calculated to explain interaction character and strength.