Mg-MOF-74: A novel material for adsorption and detection of toxic gases

This study investigated the adsorption characteristics of toxic gases such as CO, H2S, SO2, NH3, and NOx (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 these molecules and Mg-MOF-74 have adsorption interactions. CO, H2S, and NH3 molecules interact with MOF through physisorption, whereas SO2, NO, and NO2 molecules interact through chemisorption. In addition, the potential application of Mg-MOF-74 as an appropriate sensor for detecting these gas molecules is investigated by analyzing 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 significant effect on the HOMO–LUMO gap of the MOF; however, the adsorption of SO2, NO, and NO2 molecules reduces it by 51% (0.66 eV), 61% (0.52 eV), and 63% (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 to detect toxic gases.