Confinement-intensified multi-heavy-atom effect in a tetrahedral iodine cage enables unprecedented capture of trace xenon and krypton

The disposal of radioactive xenon and krypton generated by nuclear fission is essential for the zero emission of nuclear energy, while their efficient capture at low concentrations remains a daunting challenge. We present here a design philosophy for noble gas uptake by introducing the concept of the confinement-intensified multi-heavy-atom effect derived from the Lennard-Jones 12–6 potential, which is achieved by the construction of a previously unnoticed structural unit of a tetrahedral halogen cage arranged in a metal-organic framework (Cu(idc-I)). Record-high adsorption capacities of 128.58 and 20.83 cm³ cm⁻³ for Xe and Kr, respectively, were achieved at 0.1 bar and ambient temperature, along with the highest Kr Henry coefficient (10.19 mmol cm⁻³ bar⁻¹). The dense tandem-arrayed tetrahedral iodine cages, as powerful binding sites have been visualized by in situ single-crystal X-ray diffraction studies and theoretical simulations, endowing Cu(idc-I) with the ability to effectively capture trace Xe and Kr from mimic nuclear reprocessing off-gas.