Multicolored Carbon Quantum Dots-Based Expanded Fluorescence Strategy for High-Throughput Detection of Various Water Pollutants

Fluorescence nanosensors are highly in demand for the rapid detection of water pollutants due to their advantages of high economic feasibility, high-throughput, and highly sensitive response. However, previous studies have primarily focused on specific pollutants due to the limited electrical band structure of fluorescence nanosensors. Therefore, to broaden the applicability of fluorescence detection techniques, it is critical to develop a new fluorescence nanosensor with a diversified spectrum (macroscopically represented by multiple colors). In this work, four different colored carbon quantum dots (CDs) were prepared without the need for additional separation or purification steps. Through comprehensive characterization and theoretical modeling, the fluorescence colors were attributed to size effects, configuration, and the spatial location of nitrogen. The mechanism of fluorescence excitation and emission in the as-prepared nanosensor was clearly illustrated using hole–electron analysis. Furthermore, a test set comprising universal heavy metals and antibiotics was employed to investigate the feasibility of the rapid fluorescence detection of multicolor CDs. Additionally, a smartphone-app-based fluorescence color detection device was developed to complete the high-throughput in situ examination of real water samples. This work offers a new perspective on broadening the application of fluorescence detection technology and serves as a resource for rapid, high-volume, and in situ fluorescence detection of water pollutants.