Synthesis of green fluorescent carbon dots and their application in mercury ion detection†

Green fluorescent carbon dots (GCDs) were synthesized using o-phenylenediamine and ethylenediamine through a one-step hydrothermal method, thereby eliminating the need for further processing. The GCDs exhibited strong green fluorescence that was effectively quenched by Hg²⁺ and Fe³⁺, with minimal interference from other metal ions, anions, and small biological molecules. By optimizing the buffer solution, interference from Fe³⁺ was mitigated, which enhanced the robustness of the GCDs as a fluorescence probe for Hg²⁺ detection. The detection range for Hg²⁺ was 0–100 μM, with a detection limit of 300 nM. The quenching mechanism was thoroughly investigated, and the GCDs were successfully applied to detect Hg²⁺ in real water samples, yielding satisfactory results. This work highlights the potential of GCDs for practical environmental monitoring and water quality analysis.