Novel low-rank coal-based CDs for the detection of Fe³

In this study, a novel type of coal-based carbon dots (CDs) was synthesized using Inner Mongolia lignite as the carbon source and H₂O₂ as the oxidizing agent, and it was successfully applied for the detection of Fe³⁺ ions. The morphology and structure of CDs were characterized using TEM, XPS and FT-IR techniques. The results revealed that the CDs exhibited a relatively regular triangular star-like morphology with an average diameter of approximately 9.21 nm. The surface was abundant in oxygen-containing functional groups, including hydroxyl and carboxyl groups. Under ultraviolet illumination, the samples exhibited bright blue fluorescence, with a fluorescence quantum yield of up to 23.49%. When the concentration of Fe³⁺ is within the range of 6-670 µmol L^-1, a well-defined linear relationship is observed, with a detection limit of 0.123 µM. Furthermore, SiO₃^2- acts as a fluorescence restorer in the CDs-Fe³⁺ system, enabling the construction of a fluorescence quenching-recovery system based on CDs, which has been successfully applied to the detection of Fe³⁺ in soil and vegetables samples. These novel coal-based CDs exhibit promising application potential in the environmental analysis of Fe³⁺ ions.