A Redox-Active Metal–Sulfide Framework for Selective and Synergistic Removal of Iodate

Efficient removal of iodate (IO3–) from radioactive liquid waste is highly desirable for radioactive waste management and environmental protection but remains a formidable challenge due to the low adsorption capacity or insufficient removal depth resulting from the weak affinity of conventional single-function adsorbents. Here, we report a redox-active metal–sulfide framework (SCU-SnS) that enables the highly efficient decontamination of IO3– through a synergistic effect: efficient reduction of IO3– to I– by S2– sites, combined with an extremely high binding affinity between Sn4+ sites and the resulting I–. Benefiting from this synergistic effect of redox and iodination reactions, SCU-SnS features both an exceptionally high distribution coefficient (Kd = 1.58 × 106 mL/g) and a remarkable adsorption capacity of 1022.8 mg/g for IO3– removal. Notably, SCU-SnS demonstrates an unparalleled selectivity, capable of nearly quantitative removal of IO3– in the coexistence of a 100-fold excess of various competing anions, including Cl–, NO3–, CO32–, and SO42–. This synergistic strategy not only delivers a promising adsorbent for IO3– decontamination under highly competitive environments but also inspires an alternative approach to designing advanced adsorbents for nuclear waste management.