Theoretical study on the functionalization of BC₂N nanotube with amino groups

Abstract

Using density functional theory calculations, we investigated properties of a functionalized BC₂N nanotube with NH₃ and five other NH₂-X molecules in which one of the hydrogen atoms of NH₃ is substituted by X = −CH₃, −CH₂CH₃, −COOH, −CH₂COOH and −CH₂CN functional groups. It was found that NH₃ can be preferentially adsorbed on top of the boron atom, with adsorption energy of −12.0 kcal mol⁻¹. The trend of adsorption-energy change can be correlated with the trend of relative electron-withdrawing or -donating capability of the functional groups. The adsorption energies are calculated to be in the range of −1.8 to −14.2 kcal mol⁻¹, and their relative magnitude order is found as follows: H₂N(CH₂CH₃) > H₂N(CH₃) > NH₃ > H₂N(CH₂COOH) > H₂N(CH₂CN) > H₂N(COOH). Overall, the functionalization of BC₂N nanotube with the amino groups results in little change in its electronic properties. The preservation of electronic properties of BC₂N coupled with the enhancement of solubility renders their chemical modification with either NH₃ or amino functional groups to be a way for the purification of BC₂N nanotubes.