Adsorption-Induced Swellable Porous Aromatic Frameworks for High-Capacity Iodine Capture at Elevated Temperature

Efficient capture of radioactive iodine is of significant importance in nuclear waste treatment. However, under high operating temperatures in practical conditions (usually above 150°C), the efficient adsorption of iodine vapor remains a severe challenge. Traditional porous materials often suffer from a sharp decline in performance at high temperatures because of deactivation of adsorption sites in the adsorbates. In order to address this challenge, we constructed flexible porous aromatic frameworks (PAFs) with secondary amine-bridged connections, featuring an adsorption-responsive "breathing effect". At high temperatures, the flexible frameworks swell with the incorporation of iodine, which enables the accommodation of a greater volume of iodine vapor. Furthermore, abundant N-sites and π-donor functionalities within the frameworks enhance iodine adsorption through the formation of charge-transfer complexes. Consequently, the iodine vapor adsorption capacity reached 7.88 g g^-1 at 150°C, significantly surpassing that of conventional adsorbents.