Synergistic Ion Exchange‐Redox in an Ionic Covalent Organic Polymer: Enhanced Iodate Removal and Excellent Regenerability

Radioactive iodate (IO 3 – ), the dominant iodine species in nuclear wastewater, poses severe environmental threats. Here we present a dual‐functional ionic covalent organic polymer (iCOP) that integrates cationic guanidinium sites with redox‐active phenolic groups. This unique architecture enables a synergistic ion exchange–redox mechanism, where IO 3 – is rapidly captured through electrostatic attraction and hydrogen bonds, then reduced in situ to I 2 /I 3 – . The adsorbent achieves a high IO 3 – capacity of 1093.7 mg g −1 , fast kinetics, and high removal efficiency in simulated nuclear‐contaminated groundwaters (86.8% for Beishan; 95.7% for Hanford). Importantly, it is the first regenerable redox sorbent for radioactive IO 3 − remediation, retaining 74% capacity after three mild ascorbic acid treatments. Control studies with a series of iCOPs confirm that both functionalities are indispensable, with redox activity underpinning the extraordinary capacity. Density functional theory calculations further reveal a stepwise proton‐coupled electron transfer pathway and cooperative binding‐reduction behavior, establishing a design principle for porous materials that couple targeted capture with chemical conversion of hazardous radionuclides.