Highly efficient and ultrafast gaseous iodide removal by controlling the oxidation degree and size of graphene oxide membranes.

Gaseous molecular iodide is a critical volatile species in nuclear fuel reprocessing and medical isotope production, whose efficient capture in atmospheric environments is essential for ensuring environmental safety and optimizing nuclear chemical processes. For large-scale environmental engineering systems, the efficient and regulated removal of small-molecule contaminants typically demands the simultaneous fulfillment of two core performance metrics: high throughput and superior separation efficiency. Nevertheless, an inherent trade-off exists between these two critical objectives. Here, we demonstrate that tuning the reduction degree of graphene oxide affords precise control over the interlayer spacing and the formation of short Z-shaped transport pathways, enabling highly selective separation of iodine-containing gases from helium. The rGO-280 membrane achieves a CH3I rejection rate of 99.9% under CH3I/He atmospheres while maintaining excellent stability over 6 h of continuous operation. Remarkably, the membrane consistently delivers >99% rejection for multiple iodine species (CH3I, HI, and HIO3). These findings establish rGO membranes as a robust platform for high-efficiency iodine gas separation and provide a solid theoretical basis for their engineering deployment.