The adsorption of NO2, SO2, and O3 molecules on the Al-doped stanene nanotube: a DFT study.

Adsorption of pollutant gas molecules (NO2, SO2, and O3) on the surface of the Al-doped stanene nanotube was investigated within the first principle calculations of density functional theory (DFT). Adsorption mechanisms were studied by analyzing optimized structures, band structures, projected density of states (PDOS), charge density difference (CDD), molecular orbitals, and band theory. Investigation of charge transfer by Mulliken population showed that NO2 accumulated while SO2 and O3 depleted charge density on the Al-doped nanotube. The differences in band structures before and after adsorption implied that the electronic characteristics of Al-doped nanotube changed dramatically in case of NO2 adsorption, which converted Al-doped nanotube to a semiconductor material. High adsorption energy and the significant overlap between PDOS spectra indicated that the adsorption process was chemisorption for NO2, SO2, and O3 on the doped nanotube with the obtained order of O3 > SO2 > NO2. The results showed that the adsorption of NO2, SO2, and O3 occurred on the Al-doped stanene nanotube, and that all the three gas molecules could be detected by Al-doped stanene nanotube with various detection strengths.