First-Principles Study on the Selective Separation of Toxic Gases by Mg-MOF-74

This study primarily focused on the detection and separation of toxic gases such as CO, H2S, SO2, NH3, NO, and NO2 by Mg-MOF-74, as well as assessing the stability of those toxic gases on it. The calculations were performed by using density functional theory as implemented in the Gaussian-09 and Quantum ESPRESSO suites of the program. GGA-type PBE-D2 functionals with a plane wave basis set were used in the optimization of the Mg-MOF-74 crystal, and hybrid-type B3LYP and M06 functionals with the 6-31G*basis set were used in cluster calculation. The binding energies of CO and H2S with MOF were found to be in the physisorption range, whereas the energies of SO2, NH3, NO, and NO2 were found to be in the chemisorption range. Based on binding energy, hardness, and softness studies, it was found that NO and NO2 molecules were more stable in Mg-MOF-74, suggesting that Mg-MOF-74 is a good detector for NO and NO2 molecules.