Polychromatic fluorescent MoS 2 quantum dots: fabrication and off-on sensing for fluorine ions in water.

Recently, MoS 2 quantum dots (QDs) have receive widespread attention as a promising luminescent material. However, so far, little effort has been made on the multicolor emission of MoS 2 QDs. Herein, an in situ iodine doping strategy is presented and used to synthesize tunable-photoluminescent (PL) MoS 2 QDs. By fine iodine doping, the PL of the MoS 2 QDs (I-MoS 2 QDs) can be tuned in the range from 423 nm to 529 nm, which exceeds the as-reported emission wavelength range. Studies using controlled experiments and density functional theory (DFT) reveal that the change in electronic state of MoS 2 QDs is responsible for the changing PL due to iodine doping. As-synthesized I-MoS 2 QDs combined with Fe 3+ is developed as a "turn-off-on" fluorescence sensor for F - ions in water. The fluorescence probe has a fine linear response to F - ions in the concentration range of 2.5-80 μM, and the limit of detection is 1.4 μM (S/N = 3).