Blue‐Emissive Nitrogen‐Doped Carbon Quantum Dots as Highly Effective Fluorescent Nanosensor for Congo Red Sensing

ABSTRACT Based on the necessity of Congo red detection and excellent performance of the fluorescence method, nitrogen‐doped carbon quantum dots (N‐CQDs) were established through a facile and green hydrothermal method. N‐CQDs were synthesized from hawthorn leaves and N‐isopropylacrylamide and were firstly used for Congo red detection. Through the inner filter effect and static quenching principle, this as‐prepared probe was successfully applied in the sensitive and selective detection of Congo red. Combining various characterization results, well‐dispersed N‐CQDs possessed superior fluorescent property, water solubility, and stability. The blue fluorescence emitted at 438 nm when the maximum excitation wavelength was located at 365 nm. Under the optimal detecting condition, the linear range achieved 0.5–300 μM with a detection limit of 0.089 μM. More importantly, the outstanding performance of recovery experiments in real samples and temperature sensing displayed great promise for Congo red detection through N‐CQDs.