Hydrothermal synthesis of WS 2 quantum dots and their application as a fluorescence sensor for the selective detection of 2,4,6-trinitrophenol

Herein, we report a simple and green approach for the synthesis of photoluminescent WS 2 quantum dots (WS 2 QDs) from WS 2 powder by employing a hydrothermal route in the presence of NaOH. The monodispersed QDs possessed excellent water solubility, good photostability and temporal stability. The selective and sensitive detection of 2,4,6-trinitrophenol (TNP), a member of the family of nitroaromatic (NA) explosives, was demonstrated using the WS 2 QDs. Upon interaction with TNP, the PL emission of WS 2 QDs was quenched linearly over a range of 0.5 to 95 μM. The limit of detection was as low as 0.30 μM, which attests to the potential of WS 2 QDs as a TNP sensor. Electron transfer, Förster resonance energy transfer (FRET) and the inner filter effect (IFE) constituted the mechanism of quenching. Since all NAs are electron deficient, they can facilitate the PL quenching of a fluorophore by electron transfer. However, the latter two quenching mechanisms ensure the selectivity of the QDs towards TNP over other NAs. We envisage these water-soluble QDs as potential chemical sensors in the biological domain.