Creating Cu(I) Sites in an MOF for Reversible Capture of Molecular Iodine at Low Concentrations and High Temperatures
Tingting Pan, Kaijie Yang, Xinglong Dong, Jun Tao, Yu Han
Abstract
Developing adsorbents for capturing low-concentration molecular iodine (I 2 ) from nuclear plant off-gases is crucial yet poses significant challenges. Here, we report a specifically designed adsorbent, named MFU-Cu(I), which is prepared by incorporating coordinatively unsaturated monovalent Cu species into an azolate-based MOF. MFU-Cu(I) integrates excellent thermal stability, high porosity, and potent chemical adsorption sites, demonstrating superior I 2 capture performance under stringent conditions. At a low I 2 concentration of 150 ppmv, MFU-Cu(I) achieves high I 2 uptake capacities at both room temperature (3.11 g g –1 ) and 150 °C (0.2 g g –1 ), making it the most effective I 2 adsorbent to date. The ability of MFU-Cu(I) to capture I 2 at low concentrations and elevated temperatures is attributed to the Cu(I) sites firmly anchored within the MOF framework. These sites facilitate dissociative adsorption of I 2 through a redox reaction, while inhibiting the irreversible formation of CuI precipitates. Consequently, MFU-Cu(I) can be readily regenerated after I 2 adsorption via ion exchange followed by vacuum heating. The regenerability of MFU-Cu(I) represents a notable advantage over other chemical adsorbents developed for I 2 capture.