A dual-emission fluorescence sensor constructed by encapsulating double carbon dots in zeolite imidazole frameworks for sensing Pb2+.

[Display omitted] • A dual-emission ratio fluorescent sensor (N-CDs/R-CDs@ZIF-8) was developed for Pb2+. • Spinach served as carbon source for green preparation of red fluorescent CDs. • Ultrasensitive Pb2+ detection down to 4.78 nM was delivered. A novel dual-emission ratio fluorescent sensor (N-CDs/R-CDs@ZIF-8) has been constructed successfully by introducing nitrogen-doped blue fluorescence carbon dots (N-CDs) and red fluorescence carbon dots (R-CDs) into the synthetic environment of ZIF-8 by a simple stirring method. The synthesized material not only inherits the excellent optical properties of N-CDs and R-CDs and the strong adsorption and accumulation performance of ZIF-8, but also shows strong fluorescence and structural stability in extreme environments. The presence of Pb2+ strongly causes the fluorescence quenching of N-CDs, but has almost no effect on the fluorescence of R-CDs. Therefore, a ratio fluorescence sensor is developed for the determination of Pb2+. Most importantly, the real-time fluorescence response shows that the composite material has a high selectivity and good sensitivity to Pb2+ determination, and the calculated LOD is 4.78 nM(S/N = 3) (0.05–50 μM), indicating that the material can be used as a potential fluorescent sensor for Pb2+ detection. [ABSTRACT FROM AUTHOR]