Defects coordination triggers red-shifted photoluminescence in carbon dots and their application in ratiometric Cr(VI) sensing

Hexavalent chromium ion (Cr(VI)) is one of the most severe environmental nonbiodegradable pollutants. Considering its high biological toxicity, it is of great significance to establish a method for Cr(VI) analysis with high sensitivity and reliability. Therefore, a simple and sensitive ratiometric sensor is developed according to the co-ordination between Cr(VI) and carbon dots (CDs). In the presence of Cr(VI), the original CDs photo-luminescence (PL) emission at 445 nm was significantly shifted to 565 nm and gradually intensified. The coordination mechanism was investigated, the results indicated that the dual-amino groups at ortho-position of benzene ring is critical for this coordination. Under the optimal condition, a good linear relationship between the concentration of Cr(VI) and the PL intensity ratio I-565/I-445 was obtained from 120 nM to 200 mu M, with a low detection limit of 37 nM. Moreover, this method is applied into real water samples analysis with a high quality.

Automated summary

A simple and sensitive ratiometric sensor based on the coordination between Cr(VI) and carbon dots (CDs) was developed for accurate detection of Cr(VI) concentration. The study demonstrated that the dual-amino groups play a critical role in the coordination mechanism, and the method showed promising results in real water sample analysis.