Carbon dots with dual emission: A versatile sensing platform for rapid assay of Cr (VI)

In this article, we show that the conventional boron-nitrogen co-doped carbon dots (BNCDs) exhibit unique fluorescent ratiometricity in the detection of Cr (VI) due to their unique dual emission system. The 3D fluorescence spectrum study reveals that besides the commonplace emission centered at (360, 465) nm in blue fluorescence region, another center which may be corresponding to N-contain conjugation domains is found at (490, 535) nm. In the presence of Cr (VI) ions, the emission centered at (360, 465) nm is remarkably quenched due to inner filter effect, whereas the emission centered at (490, 535) nm is almost unchanged. By spectrally simulating inner filter effect using different excitation interferents in the 3D fluorescence spectrum study, accompanied with the fluorescence lifetime and absorption comparison, the sensing mechanism has thoroughly been illustrated. The versatile sensing capability of BNCDs in the different real samples not only provides a new way for the rapid determination of Cr (VI) in practices, but also demonstrates the great potential of the carbon-based materials with multiple emission possess in developing ratiometric sensing platform for rapid and accurate assay of different kinds of analytes.