Natural Deep Eutectic Solvents as Absorbing Solution and Preparation Solvent of Perovskite Nanocrystals Simultaneously for CH₃I Gas Visual Sensing

Methyl iodide (CH₃I) gas as a toxic gas causes great harm to organisms due to its high volatility and high reactivity with biological nucleophiles. Unfortunately, the sensing and detection of CH₃I gas are challenging because of the diffusive nature of the gases and its low concentrations in the environment. Herein, we have developed a fast, green, and sensitive CH₃I gas visual sensing method based on the capture technology of toxic gases by natural deep eutectic solvents (NADESs) coupled to the halide rapid exchange capability of perovskite nanocrystals (PNCs). In this strategy, NADESs are used as an absorption solution to adsorb gaseous CH₃I, while simultaneously exposing I^- through the action of the nucleophilic reagent; then, CsPbBr₃ PNCs were synthesized in NADESs and used as sensing material to achieve I^- exchange. Benefiting from the capture and enrichment of CH₃I gas, the sensitivity of the gas sensor was highly improved. The sensor exhibited the lowest detection limit (limits of detection) of 164.15 μmol/m³, below the minimum safe level for human inhalation, which is 200 μmol/m³. This breakthrough offers greater possibilities for the quantitative detection of CH₃I gas.