Study the role of MgONTs on adsorption and detection of carbon dioxide: First-principles density calculations

We investigated the adsorption behavior of CO2 molecules towards different magnesium oxide nanotubes (MgONTs) through first-principles density functional theory (DFT) computations. We also computed the energy of adsorption (Ea), the distance of adsorption (d) and Mulliken charge (Q) of the CO2 molecules which were adsorbed onto various MgONTs. The results showed that the adsorption of CO2 onto reduced MgONT is thermodynamically more favorable compared to the adsorption of CO2 onto stoichiometric MgONT. The most stable configurations were comprised of CO2 which was adsorbed onto the surface of reduced MgONT in a parallel fashion, where the CO2 molecule was located near the Mg atoms. Also, there was a considerable change in the electrical bond gap (Eg), thereby leading to a reduction in Eg and enhancing the electrical conductivity of the nanotubes. Moreover, a small recovery time (similar to 57.61 ms) was predicted for the desorption of CO2 from the exterior of the MgONT. Finally, we can conclude that the MgONT can be considered a viable candidate to be employed in CO2 chemiresistive sensors at room temperature.