Ratiometric fluorescence determination of carbon disulfide in water using surface functionalized carbon dots

Trace level of CS 2 in water causes a serious threat to the environment and living organisms. Thus, the development of reliable methods for its sensitive detection is quite necessary. Herein, we design a dual-emission platform composed of blue and yellow emissive carbon dots (B-CDs and Y-CDs) for ratiometric fluorescence determination of CS 2 . B-CDs, serving as the indicator, are functionalized by hydrophilic polyethylenimine groups on the surface, which can react with CS 2 to produce hydrophobic dithiocarbamate moieties, resulting in the aggregation of nanoparticles and quenching of blue fluorescence. In contrast, Y-CDs without polyethylenimine groups exhibit no reactivity toward CS 2 and act as the internal reference. With the increase of CS 2 concentration, the blue fluorescence of the sensing platform at 461 nm continually drops, but the yellow fluorescence at 560 nm keeps nearly constant. Correspondingly, the vivid color change from blue-white to yellow can be observed by the naked eyes, realizing the visual detection. There is a linear relationship between the fluorescence intensity ratio (I 461 /I 560 ) and CS 2 concentration in the range of 7.7–1400 μM. The detection limit is as low as 2.3 μM. Furthermore, the sensing platform is successfully applied to monitor CS 2 in real water, validating its good practicability.