Polarization-enhanced molecular traps: Halogen-functionalized MOFs achieve Xe/Kr separation via synergistic pore confinement and surface polarization

Xenon (Xe) and krypton (Kr) have a variety of medical, industrial, and environmental applications, but their separation is difficult due to their chemical inertness and similar physical properties. This study presents a dual-functional modulation strategy for designing halogen-decorated pillar-layered MOFs (LIFM-DMOF-X 2 , X = F, Cl, Br) to improve the efficiency of Xe/Kr separation. The incorporation of halogenated terephthalate linkers (BDC-X 2 ) and DABCO pillars enabled the frameworks to synergistically control the pore geometry and surface polarity via the steric and electronic effects of the halogens. LIFM-DMOF-Cl 2 exhibited optimal performance with a Xe uptake of 3.58 mmol g −1 (298 K, 1.0 bar) due to its balance between pore size (6.14 Å) and high surface area (1259.8 m 2  g −1 ). Dynamic breakthrough experiments confirmed the practical efficacy of this MOF, which showed a Xe retention time of up to 21 min/g and reusability for five cycles. GCMC simulations revealed multidimensional Xe-binding sites, including halogen bonds and π-interactions, with brominated variants showing exceptional polarization effects ( Q st  = 20.77 kJ mol −1 ). This work demonstrates the promise of halogen engineering in MOFs for nuclear off-gas treatment and noble gas capture.