A facile strategy of using MoS2 quantum dots for fluorescence-based targeted detection of nitrobenzene.

We present a simple approach for producing photoluminescent MoS2 quantum dots (QDs) using commercial MoS2 powder as a precursor along with NaOH and isopropanol. The synthesis method is particularly easy and environmentally friendly. The successful intercalation of Na+ ions into MoS2 layers and subsequent oxidative cutting reaction leads to the formation of luminescent MoS2 QDs. The present work, for the first time, shows the formation of MoS2 QDs without any additional energy source. The as-synthesized MoS2 QDs were characterized using microscopy and spectroscopy. The QDs have a few layer thicknesses and a narrow size distribution with an average diameter of ∼3.8 nm. Nitrobenzene (NB), an industrial chemical, is both toxic to human health and dangerously explosive. The present MoS2 QDs can be used as an effective photoluminescent probe, and a new turn-off sensor for NB detection. The selective quenching was operated via multiple mechanisms; electron transfer between the nitro group and MoS2 QDs through dynamic quenching and the primary inner filter effect (IFE). The quenching has a linear relationship with NB concentrations from 0.5 µM to 11 µM, with a calculated detection limit of 50 nM.