Computational exploration of the structure, stability and adsorption properties of the ZIF-9 metal-organic framework

Abstract Density Functional Theory calculations were performed in order to characterize the structural and spectroscopic features of ZIF-9 and to explore its adsorption properties with respect to hydrogen sulphide, carbon dioxide, methanol and ethanol. The spectroscopic analysis of ZIF-9 using different functionals showed that the calculations lead to results in agreement with the experimental data. Furthermore, the high water stability was predicted not only by means of a phase diagram accounting for the partial pressure of water, but also by the estimation of the energy barrier of the first step of ZnO formation. The adsorption energies of the studied molecules were further estimated, and these results suggest that methanol and ethanol are preferentially adsorbed. Post-processing calculations also showed that methanol and ethanol are stabilized by charge transfer although Bader charges analysis showed that this transfer is relatively low.