Facile and controllable synthesis of molybdenum disulfide quantum dots for highly sensitive and selective sensing of copper ions

Molybdenum disulfide quantum dots (MoS₂ QDs) were synthesized via a hydrothermal method using sodium molybdate and cysteine as molybdenum and sulfur sources, respectively. The optimal hydrothermal time was studied. Furthermore, the as synthesized water-soluble MoS₂ QDs were used as a fluorescence probe for the sensitive and selective detection of copper ions. The fluorescence of the MoS₂ QDs was quenched after the addition of copper ions; the reason may be that the transfer of the excited electron from QDs to copper ions leads to the reduction of the radiative recombination. The fluorescence quenching of MoS₂ QDs is linearly dependent on the copper ions concentration ranging from 0.1 μM to 600 μM, the limit of detection is 0.098 μM, which is much lower than that of existing methods. Moreover, the MoS₂ QDs show highly selectivity towards the detection of copper ions.