High sensitivity label-free detection of Fe3+ ion in aqueous solution using fluorescent MoS2 quantum dots

•The first report of fluorescence quenching of MoS2 QDs by Fe3+ ion, to our best knowledge.•The fluorescent MoS2 QDs–Fe3+ sensor operates conveniently and effectively in extremely low concentrations.•The fluorescent MoS2 QDs–Fe3+ sensor is label free and has good selectivity.