Insight into the structure of bimetallic metal-organic framework M/Zn-MOF-74 (M = Be, Mg, Ca, Sr, Ba): An in-silico study of the interaction with CO2, NO2 and H2O

Abstract

In this study, periodic DFT studies on the design of bimetallic M/Zn-MOF-74 (M = Be2+, Mg2+, Ca2+, Sr2+, Ba2+) were conducted to unveil the structure, electronic properties and their interaction with CO2, NO2 and H2O. The results show that the substitution of Zn2+ ion with M2+ ions resulted in band gap energy between 2.87 to 3.00 eV. The relative stability of M2+ substitution in various Zn2+ ion position is not difference significantly where M2+ ion might substitute Zn2+ ion in any position within the simulated unit cell of Zn-MOF-74. The bimetallic MOF was tested for the adsorption of various small gases such as CO2, NO2 and H2O. The interaction between CO2, NO2, H2O and M/Zn-MOF-74 indicates preferential interaction energy where NO2 is most likely to be adsorbed than the other gases with the interaction energy trend following from the most negative is NO2 < H2O < CO2.