Selective adsorption behavior of BC2N nanotubes toward fluoride and chloride

By using density functional theory calculations, the adsorption of Cl− and F− ions on a BC2N nanotube was investigated. Adsorption energies in the most stable configurations are about −0.36 and −5.65 eV for Cl− and F− ions, respectively. The adsorption of F− ion much more influences the electronic properties of the tube, in comparison with the Cl− ion, so that it is transformed from an intrinsic semiconductor with HOMO/LUMO energy gap of 2.57 eV to an extrinsic n-type semiconductor with the gap of 0.67 eV. It was found that the adsorption of both anions on the tube would facilitate the field electron emission from its surface by shifting the Fermi level to higher energies and decreasing the work function, significantly.