Mg-MOF-74: A Novel Material for Adsorption and Detection of Toxic

This study investigated the adsorption characteristics of toxic gases such as CO, H₂S, SO₂, NH₃, and NO_x (x=1,2) on Mg-MOF-74 using the framework of density functional theory as implemented in the Gaussian-09 and Quantum ESPRESSO suites of the programs. The result of the study revealed that the binding energies of CO, H₂S, NO, and NO₂ are in the range of physisorption, while those of SO₂ and NH₃ are in the range of chemisorption. Additionally, the potential application of Mg-MOF-74 as an appropriate sensor for detecting these gas molecules is investigated through the analysis of charge transfer, the HOMO-LUMO gap, density of states, and frontier molecular orbitals of both the MOF and gas molecules. The findings revealed that the HOMO-LUMO gap of bare MOF is 1.34 eV. The adsorption of CO, H₂S, or NH₃ molecules has no discernible effect on the HOMO-LUMO gap of the MOF; however, the adsorption of SO₂, NO, and NO₂ molecules reduces it by 49% (0.66 eV), 39% (0.52 eV), and 36% (0.49 eV), respectively. This suggests that the electronic properties of Mg-MOF-74 are highly sensitive to the presence of SO₂, NO, and NO₂ gas molecules, which will be immensely helpful to researchers who are creating nano-electric circuits for the detection of toxic gases.