Homogeneous Synthesis And Analytical Application Of CsPbBr₃ Quantum Dots And Their Nanocomposites

As a new type of semiconductor material,CsPbBr₃ quantum dots have high fluorescence quantum yield,narrow emission spectral linewidth and tunable luminescence in the visible region,which can effectively improve the sensitivity and selectivity of the fluorescence detection method based on it.At present,CsPbBr₃quantum dots are synthesized by high-temperature hot-injection method and supersaturated precipitation at room temperature.However,the size of perovskite products obtained by above methods are uncontrollable,and the stability of CsPbBr₃quantum dots is poor,which directly affect the application performance and prospect of CsPbBr₃ nanomaterials.In this paper,on the basis of the existing preparation methods of CsPbBr₃ quantum dots,an improved method for the preparation of CsPbBr₃ quantum dots is proposed to overcome the above shortcomings.Then,SiO₂ was introduced to encapsulate CsPbBr₃quantum dots to improve their water stability and luminescence properties.Subsequently,a fluorescence detection and analysis method based on CsPbBr₃QD@SiO₂ nanocomposite was proposed,and the feasibility of this method in qualitative and quantitative detection of nitroaromatic explosives was explored.The main research contents are as follows:?1?A size-controlled CsPbBr₃ quantum dot colloidal solution was prepared by adjusting the volume ratio of polar solvent?DMF?to the non-polar solvent?toluene?and the molar ratio of ligand to the perovskite precursor in the reaction system,.?2?On the basis of the above preparation method,introducing ammonia and tetramethyl orthosilicate?TMOS?,by adjusting the concentration of the aqueous ammonia solution and its components,while reducing the total polarity of the reaction system to effectively control the decomposition of CsPbBr₃ quantum dots,promote TMOS hydrolysis and rapid condensation to form SiO₂ coated on the surface of CsPbBr₃ quantum dots to improve the stability of CsPbBr₃ quantum dots.The product was characterized by photoluminescence spectra,Fourier transform infrared spectra and transmission electron microscopy.It was confirmed that CsPbBr₃QD@SiO₂nanocomposite was successfully prepared with good photoluminescence performance and stability.It provides a reliable basis for the application of CsPbBr₃QD@SiO₂nanocomposite in fluorescence analysis and detection.?3?A fluorescence detection method based on CsPbBr₃QD@SiO₂ nanocomposite film was proposed.The nitroaromatic explosives 2,4,6-trinitrophenol?TNP?,p-nitrophenol?PNP?and phenol?BP?which has similar structure as them were detected by fluorescence,and the relationship between the fluorescence quenching degree of CsPbBr₃QD@SiO₂ nanocomposite film and the concentration of the analyte was investigated.The results show that when the analyte is adsorbed on the CsPbBr₃QD@SiO₂ nanocomposite film substrate,the fluorescence quenching degree of the composite film has a good linear relationship with the concentration of the analyte and the analyte is detected at very low concentration,indicating the detection method has high sensitivity.At the same time,the nanocomposite film has good selectivity to the explosive molecule TNP,and is not affected by other components of the explosive material in the presence of interferents.According to the experimental results,it is feasible to validate the experimental method.