A core-satellite ZIF-67-on-MIL-167 heterojunction for robust capture and long-term immobilization of radioactive iodine via multi-center electron-donor synergy

The safe interception and permanent stabilization of radioactive iodine released during nuclear fuel processing are critical for ecological security and public health. However, traditional adsorbents for capturing and storing iodine vapor are still plagued with unsatisfactory uptake capacity, poor structural robustness. Herein, a unique core-satellite ZIF-67-on-MIL-167 (MOF-on-MOF) composite is fabricated through a controllable heterogeneous nucleation and growth route, which was designed for the efficient capture of radioactive iodine. Experimental data shown that delivers a maximum iodine vapor uptake of 5.600 g/g under dry atmosphere, representing a 2.03-fold and 1.42-fold increase compared to pure ZIF-67 and MIL-167, respectively. It is important to note that the iodine adsorption capacity of ZIF-67-on-MIL-167 is rarely influenced by the humid environment in a relative humidity of 18%. Furthermore, ZIF-67-on-MIL-167 exhibited excellent chemical and thermal stability, maintaining a stable framework structure at temperatures as high as 283 °C, and the iodine-loaded ZIF-67-on-MIL-167 exhibited an exceptionally high radioiodine outstanding iodine retention efficiency of 94.25% after being exposed to ambient conditions for 7 days. The composite material exhibited a high degree of synergy between its N-rich imidazole structure, abundant Ti−oxo clusters, and uncoordinated carboxylic (C O) functional groups. This synergy resulted in the provision of numerous active sites and the facilitation of charge transfer, thereby enabling the efficient capture of radioactive iodine. The adsorbent developed in this work is both reliable and effective, showing promise for practical application in radioactive iodine capture.