Imine Bond-Based Fluorescent Nanofilms toward High-Performance Detection and Efficient Removal of HCl and NH₃

A new kind of imine bond-based fluorescent nanofilm was developed as multifunctional materials for high-performance detection and efficient removal of hydrogen chloride (HCl) and ammonia (NH₃). The flexible, uniform, and photochemically stable nanofilms as prepared showed fast (<1 and <0.5 s), sensitive (<150 ppb and <1.5 ppm), and selective response to HCl and NH₃, respectively, and the removal efficiencies to HCl and NH₃ are 187.5 and 37.5% (w/w), respectively. A reversible earthy-red to green fluorescence color change upon adsorption of NH₃ or HCl enabled visualized monitoring of the two gases in the air. Mechanism studies revealed that the adsorption of HCl is a result of hydrogen bond formation between the analyte and the imine groups. Adsorption of NH₃, however, is a result of chemical reaction with the pre-adsorbed HCl. The applicability of the detection and removal strategies as developed was further verified by conducting the tests on real-life or simulated scenarios.