Sulfhydryl functionalized carbon quantum dots as a turn-off fluorescent probe for sensitive detection of Hg2+

Mercury ion (Hg2+) is one of the most toxic heavy metal ions and lowering the detection limit of Hg2+ is always a challenge in analytical chemistry and environmental analysis. In this work, sulfhydryl functionalized carbon quantum dots (HS-CQDs) were synthesized through a one-pot hydrothermal method. The obtained HS-CQDs were able to detect mercury ions Hg2+ rapidly and sensitively through fluorescence quenching, which may be ascribed to the formation of nonfluorescent ground-state complexes and electron transfer reaction between HS-CQDs and Hg2+. A modification of the HS-CQD surface by -SH was confirmed using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The HS-CQDs sensing system obtained a good linear relationship over a Hg2+ concentration ranging from 0.45 mu M to 2.1 mu M with a detection limit of 12 nM. Delightfully, the sensor has been successfully used to detect Hg2+ in real samples with satisfactory results. This means that the sensor has the potential to be used for testing actual samples.

Automated summary

In this study, sulfhydryl functionalized carbon quantum dots (HS-CQDs) were synthesized and used for rapid and sensitive detection of mercury ions (Hg2+) through fluorescence quenching. The HS-CQDs sensor showed a linear response in the concentration range of 0.45 μM to 2.1 μM with a detection limit of 12 nM, and it exhibited satisfactory results when detecting Hg2+ in real samples. This suggests the potential for practical application of the sensor in environmental analysis.