The optical fiber sensing platform for ferric ions detection: A practical application for carbon quantum dots

Carbon quantum dots (CQDs), as one kind of promising carbon nanomaterials, are widely used as fluorescent probes for metal ions sensing. An optical fiber sensing platform is established as a significant application of the CQDs to realize online detection in narrow space. The assembling process of the sensing probe can be accomplished by the method of in-situ polymerization without any mold in seconds. The maximum diameter of the designed sensing probe is only 220 µm. The sensing system is quite light that the total weight of the system with a 10 m-long optical fiber is only 3.2 kg, showing great potential application in field. Here, ferric ion is set as an example to test the performance of the sensing platform. The ferric ions in the concentration range of 0–250 μM can be quantitatively analysis by the proposed platform along with a detection limit of 0.6 μM, which is comparable with the method of dissolving the same concentration of the CQDs in the aqueous solution. The response time of the sensing system is only 6 s. The sensing platform provides real-time fluorescence variation. The practicability of the present platform is validated by Fe3+ detection in certified reference materials and real-world water samples. The sensing platform is one of the novel and promising applications of carbon-based materials.