Non-toxic carbon dots fluorescence sensor based on chitosan for sensitive and selective detection of Cr (VI) in water

A novel fluorescence carbon dots (CS-CDs) were prepared via a one-step hydrothermal approach using chitosan and urea as precursors. CS-CDs exhibited good selectivity and sensitivity of fluorescence response to Cr (VI) in a wide range with a detection limit of 0.59 μM. More interestingly, CS-CDs-based fluorescent hydrogel sensors were further developed for quantitative detection of Cr (VI) in water. The fluorescence signals of the composite were recorded by a smartphone and converted to grayscale parameters linearly related to concentration of Cr (VI) by Image J software. This composite showed a broad linear range of 10–300 μM and a low detection limit of 2.83 μM. All results demonstrate the great potential for the portable, low-cost and green detection of Cr (VI) in practical application.