A Fast and Efficient Hydrogen Chloride Sensor Based on a Polymer Composite Film Using a Novel Schiff-Based Triphenylamine Molecule as the Probe

Hydrogen chloride (HCl) is one of the most hazardous air pollutants and can cause significant damage to human health and the environment. Therefore, the continuous quantitative monitoring of HCl is of great practical importance. In this work, a novel triphenylamine derivative, named TPTc-DBD, with a Schiff base structure was synthesized. The molecular structure of TPTc-DBD was determined by NMR analysis, FTIR analysis and single crystal diffraction analysis. On this basis, a porous polyvinylidene fluoride (PVDF) film containing TPTc-DBD was then prepared by a spin-coating method, and its sensitivity to HCl was evaluated by naked eye and ultraviolet-visible absorption spectrum, respectively. The detection limit of the composite porous film for HCl molecules was determined to be 5.8 mg/m³. Interestingly, the composite films absorbing HCl can be reactivated by NH₃, which provides a cycle detection ability for HCl. After five testing cycles, the detection error remained below 1%. Furthermore, the microstructure of the film remained unchanged, highlighting its exceptional detection performance for HCl.