A theoretical study on surface modification of a nanosized BC3 tube using C2H4 and its derivatives

Chemical functionalization of a BC₃ nanotube (BC₃NT) with C₂X₄ (X = –H, –F, –CH₂F, –CN, –NH₂, –NO₂, –CH₃, and –OCH₃) was investigated by density functional theory calculations. It was found that C₂H₄ prefers to be added to a B–C bond of the tube wall. The interaction energies are calculated to be ranging from ?0.03 to ?40.32 kcal/mol, and their relative magnitude order is found to be as follows: C₂F₄ > C₂(NH₂)₄ > C₂H₄ > C₂(NO₂)₄ > C₂(OCH₃)₄ > C₂(CN₄)₂ > C₂(CH₃)₄ > C₂(CH₂F)₄. For chemically modified BC₃NTs with various functional groups, the functionalization energy can be correlated with the trend of relative electron-withdrawing or electron-donating capability of the adsorbates. The calculated density of states shows that the functionalization of BC₃NT with these functional groups (except C₂(NO₂)₄) can be generally classified as a certain type of “electronically harmless modification”. We believe that the preservation of electronic properties of BC₃NTs coupled with the enhancement of solubility may render the chemical modification to be an effective way for the purification of BC₃NTs. The insight provided by this theoretical study may also assist future development of BC₃NTs with targeted chemoselectivity through chemical functionalization.