Hollow Core–Shell Bismuth Based Al‐Doped Silica Materials for Powerful Co‐Sequestration of Radioactive I₂ and CH₃I

Abstract Developing pure inorganic materials capable of efficiently co‐removing radioactive I₂ and CH₃I has always been a major challenge. Bismuth‐based materials (BBMs) have garnered considerable attention due to their impressive I₂ sorption capacity at high‐temperature and cost‐effectiveness. However, solely relying on bismuth components falls short in effectively removing CH₃I and has not been systematically studied. Herein, a series of hollow mesoporous core–shell bifunctional materials with adjustable shell thickness and Si/Al ratio by using silica‐coated Bi₂O₃ as a hard template and through simple alkaline‐etching and CTAB‐assisted surface coassembly methods (Bi@Al/SiO₂) is successfully synthesized. By meticulously controlling the thickness of the shell layer and precisely tuning of the Si/Al ratio composition, the synthesis of BBMs capable of co‐removing radioactive I₂ and CH₃I for the first time, demonstrating remarkable sorption capacities of 533.1 and 421.5 mg g⁻¹, respectively is achieved. Both experimental and theoretical calculations indicate that the incorporation of acid sites within the shell layer is a key factor in achieving effective CH₃I sorption. This innovative structural design of sorbent enables exceptional co‐removal capabilities for both I₂ and CH₃I. Furthermore, the core–shell structure enhances the retention of captured iodine within the sorbents, which may further prevent potential leakage.