Functionalized boron–nitride nanotubes: First-principles calculations

With the use of density functional theory (DFT) calculations, we study the effect of functionalizing the surface of a boron nitride nanotube (BNNT) with hydroxyl (-OH) and carboxyl (-COOH) organic groups at the N and B sites. The results indicate that the -OH radical remains adsorbed in the B site whereas it is detached from the surface when added to the N site. Contrarily, the -COOH remains attached for both adsorption sites. Both functionalizations induced a magnetic moment, produced spin-polarized electronic bands, created flat impurity-like bands, decreased the band gaps, and modified the electron density of the nanotubes. All of these changes can be used to control and modify the interaction of BNNTs with other molecules of interest like drugs, heavy metals, and greenhouse gasses, among other substances. • The -OH functionalization at N site, detaches from the nanotube surface remaining physisorbed. • The functionalizations create impurity-like flat bands inside the band-gap. • Boron nitride nanotubes become spin polarized after functionalized with -OH and -COOH.