Open-ended modified single-wall carbon nanotubes: A theoretical study of the effects of purification

A density functional theory (DFT) study of purified single-wall carbon nanotube (SWCNT) molecular models has shown that open-ended carboxylated C(10, 0) and C(5, 5) are more acidic than benzoic acid, but moreover, that C(10, 0)–COOH is slightly more acidic than C(5, 5)–COOH, possibly enabling separation by chirality. In addition, an increase in the ionization potential may indicate a suppression of field emission for purified SWCNTs. Finally, we address the complexity of the large-scale DFT calculations by the application of the same level of theory but with a different basis set (SLDB) method, shown to be advantageous as compared to ONIOM.