Optimizing Iodine Enrichment through Induced‐Fit Transformations in a Flexible Ag(I)‐Organic Framework: From Accelerated Adsorption Kinetics to Record‐High Storage Density

Abstract

AbstractEfficient capture and storage of radioactive I2 is a prerequisite for developing nuclear power but remains a challenge. Here, two flexible Ag‐MOFs (FJI‐H39 and 40) with similar active sites but different pore sizes and flexibility are prepared; both of them can capture I2 with excellent removal efficiencies and high adsorption capacities. Due to the more flexible pores, FJI‐H39 not only possesses the record‐high I2 storage density among all the reported MOFs but also displays a very fast adsorption kinetic (124 times faster than FJI‐H40), while their desorption kinetics are comparable. Mechanistic studies show that FJI‐H39 can undergo induced‐fit transformations continuously (first contraction then expansion), making the adsorbed iodine species enrich near the Ag(I) nodes quickly and orderly, from discrete I− anion to the dense packing of various iodine species, achieving the very fast adsorption kinetic and the record‐high storage density simultaneously. However, no significant structural transformations caused by the adsorbed iodine are observed in FJI‐H40. In addition, FJI‐H39 has excellent stability/recyclability/obtainability, making it a practical adsorbent for radioactive I2. This work provides a useful method for synthesizing practical radioactive I2 adsorbents.