Chitin-rich shrimp shells-based nitrogen-doped green fluorescence carbon dots: New insights for multi-orbital applications.

Carbon dots (CDs), revolutionary carbon-based nanomaterial, have demonstrated tremendous potential for applications across multiple areas. Chitin-rich shrimp shells are a sustainable and renewable resource, and their utilization can turn waste into treasure. This work is dedicated to efficiently preparing nitrogen-doped green fluorescent CDs (N-CDs) for multi-modal applications from waste shrimp shells by hydrothermal methods. The detailed spectroscopic characterization reveals that the N-CDs possess excellent optical properties. The quantum yield is as high as 33.2%. Specifically, the N-CDs show excellent selectivity and sensitivity in the quantitative detection of Fe. Additionally, in response to pH changes, the surface functional groups of the N-CDs undergo protonation and deprotonation, leading to corresponding alterations in fluorescence colors. Capitalizing on this characteristic, a visual portable pH-measuring platform is developed. This platform ingeniously integrates nanoscale optical sensors with smartphone image processing technology, enabling real-time and highly accurate monitoring of environmental pH levels. Furthermore, they are ideal materials for fluorescence anti-counterfeiting detection due to their unique optical properties. This work simultaneously accomplishes the reuse of waste biomass and provides novel insights for multi-orbital applications, including metal ion detection, pH monitoring, and the anti-counterfeiting field.