Hollow Bismuth-Based Nanoreactor with Ultrathin Disordered Mesoporous Silica Shell for Superior Radioactive Iodine Decontamination

The effective removal of radioactive iodine under harsh high-temperature conditions, akin to those encountered in real spent nuclear fuel reprocessing, remains a formidable challenge. Herein, a novel bismuth-based mesoporous silica nanoreactor with a distinctive hollow yolk–shell structure was successfully synthesized by using silica-coated Bi₂O₃ as a hard template and alkaline organic ammonia for etching (Bi@HMS-1, HMS = hollow mesoporous silica). In contrast to conventional inorganic alkali-assisted methods with organic template agents, our approach yielded a material with thinner and more disordered shell layers, along with a relatively smaller pore volume. This led to a significant reduction in the physisorption of Bi@HMS-1 onto iodine while maintaining a smooth passage of guest iodine molecules into and out of the shell channels. Consequently, the resulting sorbent exhibited an outstanding iodine sorption capacity at high temperatures, achieving a chemisorption percentage as high as 96.5%, which makes it extremely competitive among the currently reported sorbents.