Precise regulation of active sites of MOFs for capture of iodine

Metal-organic frameworks (MOFs) have great potential for the capture of volatile iodine. The effect of a precise regulation of active sites in JLNU-4 (MOFs) on capture of iodine was investigated by Monte Carlo (MC) method and molecular dynamics (MD), and it was found that the larger the Zn/Cd atomic ratio, the better the iodine capture. Interestingly, compared with the meta-position regulation of Zn/Cd, the ortho-positions regulation increased the free volume of the crystal and enhanced the interactions between Cd and O with I, thus improving the capture capacity of iodine. The first-principles study revealed the charge transfer of each atom in MOFs crystal with I 2 during iodine capture and the secondary bonds with weak covalent interactions were all formed after I 2 adsorption onto MOFs. These findings provide a reference for the capture of radioactive iodine and a theoretical basis for the strategies for precise regulation of MOFs in the future. • By investigating the effects of different ratios and positions of the central metals of MOFs on iodine capture, a strategy for precise regulation of active sites in bimetallic MOFs was formed. • Compared with the meta-position of Zn/Cd atoms in MOFs, the ortho-positions regulation improved the free volume of the crystal by 0.82% and the interactions between Cd and O with I increased, thus improving the capture capacity of iodine. • MOFs have strong host-guest charge transfer and stronger interactions between the metal atoms and I 2 compared to the non-metal atoms. • The secondary bonds with weak covalent interactions are all formed after I 2 adsorption onto MOFs.