Flexible interdigitated layered framework with multiple accessible active sites for high-performance CH₃I capture

The development of adsorbent materials for effective capture of radioactive iodomethane (CH₃I) from the off-gas of used nuclear fuel reprocessing, remains a significant and challenging line of research because currently state-of-art adsorbents still suffer from low binding affinity with CH₃I. Here, we proposed a brand-new adsorption topological structure by developing a 2D interdigitated layered framework, named SCU-20, featuring slide-like channel with multiple active sites for CH₃I capture. The responsive rotating-adaptive aperture of SCU-20 enables the optimal utilization of all active sites within the pore for highly selective recognition and capture of CH₃I. A record-breaking CH₃I uptake capacity of 1.84 g/g was achieved under static sorption conditions with saturated CH₃I vapor. Both experimental and theoretical findings demonstrated that the exceptional uptake of SCU-20 towards CH₃I can be attributed to the confined physical electrostatic adsorption of F sites, coupled with the chemical nitrogen methylation reaction with uncoordinated N atoms of pyrazine. Moreover, dynamic CH₃I uptake capacity potentially allows for the capture of CH₃I in simulated real-world off gas reprocessing conditions. This study highlights the potential of SCU-20 as a promising candidate for efficient capture of iodine species and contributes to the development of effective solutions for radioactive iodine remediation.