Effects of SiO2 and CO2 absorptions on the structural, electronic and optical properties of (6, 6) Magnesium Oxide Nanotube (MgONT) for optoelectronics applications

Abstract

Studies of the effects of SiO2 and CO2 absorption on pristine single walled magnesium oxide nanotube (SWMgONT) were done by means of density functional theory. This research considered SiO2 and CO2 gases as our case study because literature studies revealed that SWMgONT acted against CO and NO gases. Based on the results calculated, it has been found that the band gap of SWMgONT is closed as a result of absorption of either SiO2 or CO2 which transformed it from semiconductor state to conductor state. The general decrease in the HOMO–LUMO energy gap of SWMgONT upon absorption of these gases exposes SWMgONT as a promising candidate for sensor applications. In terms of optical absorption, the calculated optical band gap of 2.5 eV which fell in the range 1.2 eV – 2.8 eV exposed the pristine SWMgONT as better photocatalyst. SWMgONT showed higher absorptions with SiO2 and CO2, higher optical refractions and transmissions were also observed as a results of interactions with these gases. So there are significant differences in the absorption spectra for SWMgONT, SiO2MgONT and CO2@MgONT even thou they have the same geometric configurations. The presence of absorption peaks above 2 eV revealed that SiO2@MgONT and CO2@MgONT are potential candidates for the next generations UV–Vis sustainability science and technology such as LED, TMTs and optical lens applications.