An aqueous solution of fluorescent MoS2 quantum dots toward a sensitive and selective probe for Fe3+: A tri-mode spectroscopic sensing technique

In this work, MoS2 quantum dots (MSQDs) of average size-3.0 +/- 1.2 nm in aqueous medium were synthesized by simple technique. Three different emissive sites of MSQDs were observed from the time-resolved photo-luminescence decay curves with an average lifetime of 3.75 +/- 0.40 ns. The high fluorescence quenching ability toward heavy metal ions of synthesized MSQDs was used for Fe3+ ion sensing, and sensitivity was 7.9 x 10-4 mu M-1. The limits of detection and quantification were-0.24 and-0.71 mu M, respectively. The zeta potential (zeta) of bare MSQD was-28.0 mV and was more positive in the presence of Fe3+ compared to other metal ions. It is observed that the value of zeta became more positive with increasing Fe3+ ion concentrations. Hence, tri-mode sensing techniques were used for sensing different metal ions and showed excellent selectivity toward Fe3+ ions.