One-pot Synthesis of High-performance Green-emitting Carbon Dots for Cd²⁺ Sensing and Anti-counterfeiting Applications

This study presents a facile one-pot solvothermal synthesis of high-performance green fluorescent carbon dots (G-CDs) using o-phenylenediamine and ethylenediamine as precursors. The G-CDs show excellent optical, temporal, and chemical stability. Notably, they exhibit the highest quantum yield of 24.2% in ethanol and a strong green emission peaking at 546 nm under 440–490 nm excitation. In addition, G-CDs have outstanding salt resistance and multi-solvent compatibility. Due to its bright photoluminescence, G-CDs can be used as a secure ink for anti-counterfeiting. More remarkably, Cd²⁺ ions can efficiently quench the fluorescence of G-CDs with a detection limit of 0.152 µmol/L, enabling accurate quantification of Cd²⁺ in water systems. The simple synthesis of high-performance G-CDs expands their applicability in sensing and bioimaging.