A novel fluorescent nanoprobe based on potassium permanganate-functionalized TiC QDs for the unique "turn-on" dual detection of Cr and Hg ions.

Titanium carbide quantum dots (TiC QDs) were synthesized by ammonia-assisted hydrothermal method. We also synthesized potassium permanganate (KMnO)-functionalized TiC QDs (Mn-QDs) by modifying TiC nanosheets with KMnO and then cutting the functional nanosheets into Mn-QDs. The TiC QDs and Mn-QDs were characterized by fluorescence spectroscopy (FL), Fourier transform infrared spectroscopy (FTIR), UV-vis spectrophotometry (UV-vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Furthermore, the modified Mn-QDs have strong luminescence ability and good dispersion stability, which can be used for Cr and Hg double ion detection with enhanced fluorescence specificity. Cr/Hg and negatively charged Mn-QDs are bound together by electrostatic interactions. Meanwhile, the surface of Mn-QDs is rich in functional groups, which interacts with Cr/Hg to modify the surface traps, leading to defect passivation and exhibiting photoluminescence enhancement. For the dynamic quenching produced by the interaction of Mn-QDs with Hg within 50 μM, it may be caused by the complex formation of Hg trapped by the amino group on the surface of Mn-QDs. The detection limits for Cr and Hg were 0.80 μM and 0.16 μM, respectively. The recoveries of Cr and Hg ions in real water samples were 93.79-105.10% and 93.91-102.05%, respectively, by standard addition recovery test. In this work, the application of Mn-QDs in Cr and Hg ion detection was researched, which opens a new way for its application in the field of detecting heavy metal ions.