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.