Iodine capture and high-efficiency membrane-enabled polyiodide separation by a two-dimensional Cu(I)-MOF

Abstract

The efficient capture and separation of radioactive iodine (I2) and polyiodide ions (I3−, I5−)from both vapour and aqueous environments are crucial for radioactive iodine management and environmental remediation. Here, we report a two-dimensional copper(I)-metal-organic framework (Cu-MOF) constructed from a TPPA ligand and CuI, which exhibits high thermal and structural stability. The synthesised Cu-MOF effectively captures iodine vapour over a wide temperature range, with a high adsorption capacity of up to 1.75 g g−1 and an excellent removal efficiency of ∼94% in the methanol solution. Structural and spectroscopic analyses show that iodine adsorption is driven by synergistic charge-transfer interactions between iodine and π-electron-rich aromatic ligands, as well as uncoordinated nitrogen donor sites. These interactions lead to the in situ formation and stabilisation of polyiodide species (I3−, I5−) within the framework. Such interactions cause significant electronic changes, resulting in a notable narrowing of the optical band gap and nearly a 100-fold increase in electrical conductivity. Additionally, a Cu-MOF-based composite membrane enables fast and efficient separation of aqueous polyiodide ions through vacuum-assisted filtration, achieving rejection efficiencies above 96%. Cu-MOF membrane can rapidly decontaminate iodine-polluted water with an uptake capacity of 24 g g−1, established through a vacuum-separation breakthrough experiment. By combining vapour- and solution-phase iodine capture with membrane-assisted separation of aqueous triiodide ions within a single Cu-MOF platform, this work presents a versatile approach for multifunctional iodine management. © 2026 Elsevier B.V.