A novel fluorescent nanoprobe based on potassium permanganate-functionalized Ti3C2 QDs for the unique turn-on dual detection of Cr3+ and Hg2+ ions

Titanium carbide quantum dots (Ti3C2 QDs) were synthesized by ammonia-assisted hydrothermal method. We also synthesized potassium permanganate (KMnO4)-functionalized Ti3C2 QDs (Mn-QDs) by modifying Ti3C2 nanosheets with KMnO4 and then cutting the functional nanosheets into Mn-QDs. The Ti3C2 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 Cr3+ and Hg2+ double ion detection with enhanced fluorescence specificity. Cr3+/Hg2+ 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 Cr3+/Hg2+ 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 Hg2+ within 50 mu M, it may be caused by the complex formation of Hg2+ trapped by the amino group on the surface of Mn-QDs. The detection limits for Cr3+ and Hg2+ were 0.80 mu M and 0.16 mu M, respectively. The recoveries of Cr3+ and Hg2+ 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 Cr3+ and Hg2+ ion detection was researched, which opens a new way for its application in the field of detecting heavy metal ions.

Automated summary

Titanium carbide quantum dots (Ti3C2 QDs) were synthesized using ammonia-assisted hydrothermal method, and potassium permanganate (KMnO4)-functionalized Ti3C2 QDs (Mn-QDs) were obtained by modifying Ti3C2 nanosheets with KMnO4. The luminescent Mn-QDs showed good dispersion stability and were able to specifically detect Cr3+ and Hg2+ ions. The interaction between negatively charged Mn-QDs and Cr3+/Hg2+ was due to electrostatic interactions and surface functional groups. The detection limits for Cr3+ and Hg2+ were 0.80 μM and 0.16 μM, respectively.