Fast and Quantitative Electrical Detection of Iodine Based on a Polymer of Intrinsic Microporosity

Rapid, sensitive, and high-fidelity detection of toxic radioiodine species is of great importance for first responder activities in case of nuclear accidents. Robust active materials that enable concise device processing and direct online electrical detection of vaporous iodine under ambient conditions are promising and urgently required. Here, we explore the use of a polymer of intrinsic microporosity (PIM-1) as the sensing layer to directly detect the real-time iodine vapor using the electrochemical impedance spectroscopy (EIS) technique. Good solubility of PIM-1 makes it easy for thin film fabrication, while the intrinsic microporosity endows the sensor with strong signal amplification capability. The sensor exhibits marked electrical responses to iodine vapor, with high chemical selectivity (>105× over air, methanol, ethanol, and water), fast response (60 s at room temperature), as well as remarkable resistance change (107× at 30 °C for 5 min). The I2 adsorptive sensing is reversible by simple heating in the air enabling the sensor to be used for at least five cycles. In addition, the resistance change is linearly related to the iodine vapor concentration in the whole range tested, making it useful not only for the qualitative detection of iodine leakage but also for quantification. The report here demonstrates that merging EIS and PIMs can be a useful tool for the electrical sensing of gaseous toxins in the environment.