Ligand‐ and Silver‐cluster‐induced Iodization Effect for Benchmark Iodine Capture in MOFs at High Temperatures

ABSTRACT Efficiently capturing radioactive iodine from off‐gases of the spent fuel reprocessing plant is crucial yet poses significant challenges. Traditional silver‐loaded zeolites suffer from low silver loading and silver aggregation, reducing iodine removal performance. Here, we demonstrate that ligand‐ and silver‐cluster‐induced iodization is an effective strategy to enhance iodine capture in MOFs even at high temperatures. The electron‐rich N‐containing ligands transfer charge to guest iodine molecules to induce the formation of polyiodide ions, while the highly dispersed silver clusters dissociate with ligands and enable the permanent iodine immobilization in the form of iodides. A key insight from mass spectra reveals the presence of a range of iodization products, including [I 3 ] − , [I 5 ] − , [I 7 ] − , and [I 8 ] 2− . Benefiting from the dual iodization effects, the benchmark Ag‐2‐Methylimidazole, integrating suitable pore topologies and multiple chemical adsorption sites, achieves adsorption capacities 5.23 g/g at 150°C, surpassing most previously reported adsorbents at high temperatures. Besides, a simple layer‐by‐layer fabrication process can produce bead‐based adsorbents to enhance the dispersion and accessibility of Ag‐MOFs for industrial applications. The synergetic iodization effect included by ligands and metal nodes in MOFs would stimulate the development of new materials for the safe treatment of radioactive iodine.