An efficient and fast strategy for the ratiometric detection and differentiation of nitrophenols using triple-excited carbon dots under neutral conditions

Nitrophenols, essential chemical feedstocks, are released into the ecosystem during food production. Given their toxicity, persistence and health risks, accurate visual field analyzers for nitrophenols are essential. Herein, we synthesize novel triple-excited carbon dots (TE-CDs) and design an excitation-driven ratiometric detection method to quantitatively determine and distinguish nitrophenols under neutral conditions. Specifically, the excitation intensities of TE-CDs are selectively quenched by the localization of inner filter effect in the presence of nitrophenols. Nitrophenols can be divided into 4-nitrophenol, 3-nitrophenol and 2-nitrophenol with detection limits of 78 nM, 115 nM and 96 nM. In addition, mixed nitrophenols can be further distinguished by means of hierarchical cluster analysis and linear discriminant analysis with high reliability. Furthermore, a smartphone-integrated sensor with a TE-CDs-based film is designed, demonstrating commendable accuracy and precision in actual applications. Consequently, this study presents a robust methodology for in situ monitoring and intelligent sensing of nitrophenols under neutral conditions.