Regenerable Cu₂O/SiO₂ for efficient methyl iodide capture: copper-vacancy-driven cleavage mechanism

Developing metal-based adsorbents capable of high-temperature methyl iodide (CH₃I) capture and facile regeneration still poses a significant challenge. Herein, the micro-spherical cuprous oxide supported on silica (Cu₂O/SiO₂) was synthesized for the investigation of CH₃I adsorption behavior. The Cu₂O/SiO₂ material showed a high adsorption capacity (1204 mg/g) for CH₃I at 150 °C. After regeneration, the spent material retained over 90% of its initial capacity with its Cu₂O structure preserved. Combined with density functional theory (DFT) calculations, these results revealed that the underlying adsorption mechanism of CH₃I onto Cu₂O primarily involved the cleavage of CH₃I facilitated by the readily formed copper vacancies in the Cu₂O lattice, ultimately leading to the formation of CuI. This work provided a facile regeneration strategy applicable to a wide range of iodine adsorbents for radioactive CH₃I capture.