Preparation Of Zinc Selenide Quantum Dots Under Ultraviolet Light

Due to its symmetrical distribution of emission spectrum,single wavelength excitation,narrow width,high stability,difficult photolysis and size dependence,quantum dots are more suitable as fluorescent probes compared with traditional organic dye fluorescent probes.The materials of quantum dot fluorescent probe are cadmium quantum dot and zinc quantum dot.Core-shell quantum dots can modify the surface defects of individual quantum dots to improve their stability and luminous performance.In this experiment,ZnSe/ZnS quantum dots were prepared by water phase synthesis method catalyzed by ultraviolet light at room temperature and pressure,without the traditional water phase synthesis method,such as high temperature and high pressure,high cost,complicated operation steps and the by-products that may cause environmental pollution.Taking zinc acetate dihydrate?Zn?CH₃COO?₂·2H₂O?as the main body,sodium selenite?Na₂SeO₃?as the ligand and thioacetic acid?TGA?glutathione?GSH?as the sealing agent,the raw materials are economically easy to obtain,in line with the requirements of green environmental protection,and the operation is safe and simple.By adjusting the PH value,illumination time,ratio of reactants,such as experiment condition,exploring the preparation has good dispersion and time stability and luminescence properties of ZnSe/ZnS quantum dots administered core-shell structure of the optimal growth conditions and compare the TGA,GSH and ZnSe/ZnS core-shell structure under three kinds of modified state administered ZnSe quantum dot size,distribution uniformity,surface defect,and time stability of the difference.Ultraviolet irradiation can stimulate free electrons to trigger chemical reactions.In this study,sulfur-based acetic acid?TGA?and glutathione?GSH?were used as stabilizers and dispersants to control the growth of quantum dots and obtain evenly dispersed quantum dots.The introduced photosensitive material is also the S source formed by ZnS.The crystal structure and optical properties of quantum dots were characterized by X-ray diffraction?XRD?,electron microscopy?EM?,energy dispersion spectrometer?EDX?,photoluminescence spectroscopy?PL?and UV-vis.Considering that there are few reports on such synthesis methods and the data are not perfect,this experiment explored such preparation methods in depth and made a detailed supplement to various influencing factors and synthesis conditions for the first time.The experimental results show that ZnSe quantum dots are coated with ZnS shells,and the fluorescence characteristics and stability of quantum dots are greatly improved.The optimal synthesis conditions of ZnSe/ZnS core-shell quantum dots are obtained based on theoretical analysis.The results show that GSH-modified quantum dots have better stability and fewer surface defects than TGA-modified quantum dots.ZnS shell growth can effectively improve this defect,but too thick shell will lead to quenching of intrinsic radiation.The optimal experimental conditions after optimization were the ZnSe/ZnS core-shell structure modified by GSH and the optimal growth conditions:PH=9 at room temperature,the growth time was 23 minutes,and the molar ratio of zinc:glutathione:selenium was 3:4:1.The prepared ZnSe quantum dots are uniformly stable,and the monolayer ZnSe quantum dot films can be observed under the electron microscope.Experimental results show that the core-shell structure can not only enhance the fluorescence characteristics of ZnSe quantum dots,but also reduce their surface defects.The results showed that the fluorescence properties of the ZnSe/ZnS core-shell structure modified by GSH were doubled,the time stability was increased by more than 10 times,and the antioxidant capacity was enhanced.