Moisture–resistant and ppb–level trace chemical warfare agent optical gas sensor based on ZIF–67 3D photonic crystals with structural engineering

The rapid and trace detection of sulfur mustard (SM), a classical hazardous chemical warfare agents (CWAs) causing irreversible health damages and fatal, is an urgently serious issue for security safeguard but remains challenges especially in real-time changing atmospheric humidity. Herein, a zeolite imidazolate framework–67 (ZIF–67) three–dimensional (3D) photonic crystal optical sensor has been designed and proposed to detect trace SM simulants 2–chloroethyl ethyl sulfide (CEES). Compared to traditional semiconductors, the optical sensor can work at room temperature and shows significant moisture resistance. At real-time relative humidity (RH) of 35%, the sensor exhibits excellent selectivity among seven interfering gases due to the co-interactions of metal sites Co atoms of ZIF–67 via Co···Cl and Co···S with CEES (C4H9ClS), the ultralow detection limit (16.5 ppb), ultrafast response (0.5 s) for CEES can benefit from the ordered structure of ZIF-67 3D photonic crystal and its complete photonic bandgap. Most importantly, at higher RH 50%–95%, the sensor shows excellent moisture resistance and still keeps excellent selectivity, ultralow detection limit (19.1 ppb), ultrafast response (0.5 s), long–term stability and reusability for CEES even at RH 95%, warranting its utility as a moisture–resistant trace chemical warfare agent optical sensor.