The adsorption of bromomethane onto the exterior surface of aluminum nitride, boron nitride, carbon, and silicon carbide nanotubes: A PBC-DFT, NBO, and QTAIM study

Abstract

The adsorption of bromomethane (CH3Br) onto the outer surface of the pristine armchair (5,5) single-walled aluminum nitride nanotube (AlNNT), boron nitride nanotube (BNNT), carbon nanotube (CNT), and silicon carbide nanotube (SiCNT) were investigated using density functional theory (DFT). The geometry optimization was performed by using the PBEPBE/6-31G(d) level of theory through 1D periodic boundary conditions (in which, each unit cell containing 40 atoms). Moreover, NBO and QTAIM analyses were also performed by using the same level of theory but using the complete nanotubes (each nanotube consists of 200 atoms). For further investigation, single point energy calculations were applied to each system using the CAM-B3LYP/DEF2-TZVP level of theory. The obtained adsorption energies indicate that among all of the aforementioned nanotubes, AlNNT exhibits the strongest affinity for the adsorption of the CH3Br molecule with the most negative adsorption energy. Based on the NBO and QTAIM results, it can be inferred that CH3Br tends to be chemisorbed onto the AlN and SiC nanotubes, whereas, in the case of CNT and BNNT, the adsorption is through weak van der Waals interactions and a physisorption process. Therefore, the results of this work may be useful in designing new types of nanosensor devices.