One-pot hydrothermal synthesis of water-dispersible ZnS quantum dots modified with mercaptoacetic acid

ZnS quantum dots (QDs) were prepared and modified in situ with mercaptoacetic acid (MAA) via a facile and environmentally friendly one-pot hydrothermal method. The resulting MAA-modified ZnS QDs (ZnS(MAA) QDs) demonstrated a cubic β-sphalerite structure, spherical morphology and controllable crystal size in the range of 4–10 nm depending on the reaction time, as characterized by X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy methods. The optical properties were investigated by photoluminescence spectroscopy, which showed that the fluorescence intensity increased with reaction time. After storing for 6 months, the fluorescence intensity of ZnS(MAA) QDs retained about 50% of its initial value without any peak shift.