Fe-doped carbonized polymer dot-based fluorescent sensor with "turn-on" property for hydrazine hydrate detection

It has become a significant problem to develop and improve carbonized polymer dot (CPD)-based fluorescence sensors with environmental detection features. In this study, fluorescent "turn on" sensors of CPDs were prepared by a one-step hydrothermal method using o-phenylenediamine (o-PD) and ferric chloride (FeCl₃) as raw materials. Fe-doped CPDs exhibited excellent fluorescence properties, stability, and the sensitive and selective "turn on" detection of hydrazine hydrate (N₂H₄·H₂O). In this detection system, Fe³⁺ acts as an effective fluorescence inhibitor that inhibits the yellow fluorescence emission from CPDs, while Fe³⁺ is reduced upon the addition of the N₂H₄·H₂O reducing agent. The fluorescence intensity of CPDs gradually increased with the increasing concentration of N₂H₄·H₂O, while the limit of detection (LOD) could reach 0.168 μM. In addition, CPD-based polyvinyl alcohol (CPDs@PVA) films were also prepared, which still maintained excellent sensitivity to N₂H₄·H₂O. The results show that CPDs and their composite films can detect N₂H₄·H₂O with good detection performance.