Nanohybrid of Cu2O–Ti3C2T x as a Silver-Free MXene Sorbent for Iodine Gas Capture from Nuclear Waste

Abstract

The capture of volatile radioiodine from nuclear fuel reprocessing off-gas streams remains a critical challenge due to the high volatility, long half-life, and biological uptake of 129I from the environment. Although silver-based sorbents provide strong iodine chemisorption, their high cost and regulatory classification as mixed radioactive-hazardous waste motivate the development of alternative materials. Here, we report a silver-free Cu2O–Ti3C2Tx MXene hybrid for iodine gas capture at 150 °C. Structural and compositional analyses confirm the formation of Cu2O nanoparticles on Ti3C2Tx nanosheets and their subsequent conversion to thermodynamically stable CuI upon static iodine gas exposure. The nanohybrid achieves an iodine mass loading of up to 1115 mg/g. The iodine-loaded hybrid was further consolidated by spark plasma sintering into a mechanically self-supporting CuI–Ti3C2Tx monolith that retained the CuI phase and exhibited a seven-day cumulative normalized iodine loss of 1.64 g/m2, corresponding to only 0.076% of the initial iodine inventory during modified ASTM C1308–21 leach testing. These results demonstrate the potential of Cu2O–Ti3C2Tx MXene as a copper-based alternative to silver sorbents for elevated-temperature iodine gas capture.