Nanoarchitecturing hybridized metal-organic framework/graphene nanosheet for removal of an organic pollutant

In this work, the mechanism of malachite green (MG) interaction has been evaluated by the density functional theory (DFT) calculation over a metal–organic framework/graphene nanosheet (MOF/G-sheet) and compared with its pristine counterparts (i.e., graphene nanosheet and graphene oxide (GO)). For the hybrid MOF/G-sheet, a dome-like ZIF-8 crystal mounted on G-sheet (G-ZIF-8) was found the optimal morphology with a stable structure, which approved the experimental results. Three different symmetrical sites across the G-ZIF-8 structure namely top, bridge, and free sites were studied to optimize the interaction position and calculate the adsorption energy. The graphical plot of frontier high occupied molecular orbital (HOMO) and low unoccupied molecular orbital (LUMO) of the MG molecule and adsorbents were calculated by the B3LYP method and LANL2DZ/6-311G(d,p) basis sets. TDOS plots illustrated that the G-ZIF-8 hybrid nanocomposite was more stable than the others. The best site for the MG molecule adsorption over G-ZIF-8 was the top site with the best distance of 8 Å and adsorption energy of −0.2812 Hartree. The adsorptive removal strength for MG in all simulated compounds was found to be in the order of G-ZIF-8 > G-sheet > GO.