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

Abstract

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 photoluminescence 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 × 10−4 μM−1. The limits of detection and quantification were ∼0.24 and ∼0.71 μM, respectively. The zeta potential (ζ) 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 ζ 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.