Highly fluorescent nitrogen-doped carbon dots for selective and sensitive detection of Hg2+ and ClO- ions and fluorescent ink

A facile one-step hydrothermal strategy using citric acid, ethylenediamine, and fluorescein as the precursors for the synthesis of fluorescent nitrogen-doped carbon dots (NCDs). The obtained NCDs exhibited blue fluorescence with maximum excitation/emission wavelengths at 350/447 nm and fluorescence quantum yield was up to 61%. The blue emission of the NCDs was independent of the excitation wavelength from 330 to 390 nm, while they possessed spherical morphology. The NCDs were also very stable in a wide pH range and in solutions with high ionic strength. More specifically, the fluorescence of the NCDs was effectively quenched by mercuric (Hg2+) and hypochlorite (ClO-) ions, suggesting that the NCDs can be utilized for detecting Hg2+ and ClO- with high selectivity and sensitivity. The linear ranges and limits of detection were 0.05-30 mu M and 19 nM for Hg2+, and 0.1-70 mu M and 90 nM for ClO-, respectively. Moreover, the NCDs were applied for detecting Hg2+ and ClO- in water samples with satisfactory results, indicating its sensing potential in environmental monitoring. Additionally, it was proven that the synthesized NCDs could be utilized as a fluorescent ink.

Automated summary

In this study, fluorescent nitrogen-doped carbon dots (NCDs) were synthesized using a facile one-step hydrothermal strategy with citric acid, ethylenediamine, and fluorescein as precursors. The NCDs exhibited blue fluorescence with high quantum yield and stability, making them suitable for detecting heavy metal ions and hypochlorite with high sensitivity and selectivity. Additionally, the synthesized NCDs showed potential for environmental monitoring applications.