MAA-modified and luminescence properties of ZnO quantum dots

The precursor of ZnO has been prepared by refluxing in ethanol at 70°C for 4 h using ZnAc2·H2O as the initial agent. Then ZnO has been prepared from the reaction of LiOH·H2O and the precursor. The ZnO is modified by mercaptoacetic acid (MAA) and detected by SEM and XRD. These ZnO particles have single phase, like-sphere and size of 4.6 nm. The modified effectivity of MAA for the quantum dots (QDs) has been investigated with UV-visible and fluorescence analysis, and the mechanism and property of ZnO light emitting have been discussed under given conditions. The reasons why the fluorescent emission peak of surface defects disappear and the exciton emission peak increase are that MAA effectively covers the surface defects of ZnO and stably coats ZnO particles. At the same time, the effect of the added amount of the MAA, temperature and electrolyte on light-emitting properties of modified product has also been studied. The result shows that the modified ZnO QDs have good fluorescence property, stability and suitable capability of resisting electrolyte. These results are important for biological analysis.