One-pot hydrothermal method of green-synthesized nitrogen-doped carbon quantum dots for ultra-sensitive dual detection of tannic acid and Hg2+ ions

Green-synthesized nitrogen-doped carbon quantum dots (N-CQDs), offering an excellent platform for the ultra-sensitive dual detection of tannic acid and Hg²⁺ ions, were explored in this work. The N-CQDs were synthesized in a straightforward, cost-effective, and environmentally friendly hydrothermal method. These N-CQDs exhibited remarkable and dynamic “on-off-on” luminescent characteristics, demonstrating an exceptional sensitivity and selectivity towards tannic acid and Hg²⁺ ions. The specific interactions between the N-CQDs and tannic acid, along with the reversible binding with Hg²⁺ ions, contribute to the distinct dual-detection capabilities. The sensing system covers a linear concentration range of 10–80 µM to tannic acid and 0.1 to 1 nm for Hg²⁺, showcasing its versatility for different concentration range with a lower detection limit of 25 nM and 3 nM, respectively. Furthermore, the N-CQDs displayed high stability and minimal interference from typical interfering species, making them a desirable tool for environmental monitoring and quality control. Validation through real sample analysis substantiates the accuracy and reliability of the developed sensing approach in practical scenarios. This study not only underscores the promise of green-synthesized N-CQDs as enhanced fluorescence probes but also contributes to the development of efficient and environmentally friendly materials for dual sensing applications.