Interpreting the CO2 adsorption on functionalized organic group of IRMOF-1: A B3LYP DFT based study

Density Functional Theory (DFT) calculations techniques in terms of energetic and electronics properties are used to study CO2 adsorption in NH2-, OH-, COOH-, Br- and Cl-functionalized IRMOF-1. Geometry optimization, density of states (DOS), and energy analyses were performed to investigate the adsorption phenomenon. First, we examined the geometrical as well as the electronic structures of functionalized IRMOF-1 (actually functionalized H2BDC as representative section) before and after interaction with CO2, in order to compare and comprehend the relationship between their chemical structure and their related properties. The binding properties have been calculated and analyzed theoretically for pristine H2BDC and X-H2BDC as well as their complex forms with CO2 molecule in terms of binding energies, band structures, total density of states, and Mulliken charges. The finding showed larger interaction energy in COOH-H2BDC (-22.3125 kJ/mol) and somewhat in OH-H2BDC (-12.8625 kJ/mol) and NH2-H2BDC (-12.6000 kJ/mol) complexes compared to less interaction energies in Br-H2BDC (-10.2375 kJ/mol) and Cl-H2BDC (-6.0375 kJ/mol) complexes. The type of interaction between CO2 with pristine H2BDC and X-H2BDC was studied with understanding the HOMO and LUMO energies.