Aqueous-Phase Confined Assembly of Single-Atom Chains inside Carbon Nanotubes Enabling Ultrafast Iodine Removal and Enhanced Catalysis.

Extracting radioactive iodine from waste solutions and directly converting it into functional materials with controllable structures is crucial. We report a liquid-phase strategy for confined assembly of single-atom iodine chains inside single-walled carbon nanotubes (SWCNTs). SWCNTs with diameters of 0.7-2.2 nm predominantly host single-atom chains, enabling charge transfer from tube walls to chains, forming I3- units and inducing positive charge delocalization on the tube surface, which is more pronounced in larger diameters. This charge delocalization makes large-diameter SWCNTs robust adsorbents for rapid iodine removal via electrostatic interactions across broad temperature (2-60 °C) and pH (1-5.6) ranges, achieving an exceptional removal rate (53.7 mgI2·gSWCNT-1·min-1) surpassing most reported adsorbents and enabling continuous-flow capture. The single-atom chain Ix@SWCNT also serves as a highly efficient and stable catalyst for thiol coupling, boosting the reaction rate 21-fold over homogeneous molecular I2. Spectroscopy and calculations elucidate the charge delocalization mechanism within Ix@SWCNT.