Room-temperature phosphorescence based on chitosan carbon dots for trace water detection in organic solvents and anti-counterfeiting application

Trace water is known to be an impurity in organic solvents, having an adverse effect on the chemical reaction or environmental safety. Developing a green, facile and non-toxic method for detecting trace water in various organic solvents is still a challenge. Distinct form conventional fluorescent probes, room-temperature phosphorescence (RTP) test paper (TP) has aroused wide concern owing to its characteristic optical performance, including long afterglow and non-background interference. Herein, we fabricated a new kind of RTP-TP on the basis of chitosan carbon dots (CDs). The anchoring effect of polyvinyl alcohol (PVA) promoted the restriction of vibration/rotation and hindered the non-irradiative quenching of CDs by forming intermolecular hydrogen bonds. However, water molecules could interrupt these hydrogen bonds and therefore the RTP phenomenon would be disappeared. Further, the RTP-TP was used to detect trace water in various organic solvents with high efficiency, excellent stability, and reliability. In addition, the CDs-PVA solution can be also used as anti-counterfeiting ink via various printing methods.