Preparation And Properties Of Borate/Carbon Quantum Dot Complex Research

With the end of the third industrial revolution,a series of new intelligent industries,represented by electronic information technology,have been created,which puts forward higher requirements for the development and utilization of photoelectric materials.At present,photoelectric materials have begun to concentrate their efforts in a number of industries,showing a trend of combining with energy,medical,information and other aspects,and emerging a number of new materials,new technologies and new directions,which further provides a new growth point for the development of the photoelectric industry.Developments in the emerging field of nanotechnology have enabled researchers to not only synthesize different types of carbon quantum dots,but also to apply them in different fields based on their unique physicochemical properties.Most carbon quantum dots are centered around the study of luminescence performance in aqueous solutions,because carbon quantum dots will be quenched due to aggregation induction in the solid state,which leads to the great limitation of carbon quantum dots in optoelectronic applications.Borate has attracted wide attention due to its diversity,high vacuum ultraviolet transmittance,chemical stability and other characteristics,BO₃^3-has complex structural characteristics and multiple coordination methods,is an excellent potential luminescent matrix material.In this paper,using yttrium borate as luminescent substrate,nitrogen doped carbon quantum dots（N-CQDs）with blue emission or rare earth ion europium ion(Eu³⁺)with red emission were loaded onto borate substrate to realize solid fluorescence of carbon quantum dots,and applied in anti-counterfeiting identification and toxicant detection.The specific research is as follows:Firstly,YBO₃/N-CQDs composites doped with different content of carbon quantum dots were prepared by hydrothermal method using YBO₃ as matrix.The results show that under the doping of a certain number of carbon quantum dots（N-CQDs）,the YBO₃/N-CQDs complex still maintains the lattice structure of YBO₃matrix,all belong to hexagonal shrapnel structure,and the appearance is petal-like microspheres stacked with sheet structures.With the gradual increase of carbon quantum dot（N-CQDs）doping content,the center position of the petals of the composite began to be filled with a lamellar structure,and its fluorescence emission intensity also gradually increases.Secondly,a series of rare earth europium ion doped YBO₃:X%Eu³⁺red phosphor was prepared,and the experimental data showed that the doping of rare earth ions Eu³⁺did not change the lattice structure of YBO₃,but occupied the position of Y³⁺in the original matrix.When the doping content of rare earth ion Eu³⁺reaches 10%,the luminous intensity of phosphors reaches a maximum under wavelength excitation of 254 nm.YBO₃:10%Eu³⁺/N-CQDs composites were prepared by hydrothermal doping of different amounts of carbon quantum dots using YBO₃:10%Eu³⁺phosphor as matrix.The results showed that the introduction of N-CQDs caused the petal structure of the matrix to be gradually dispersed,and the original spherical structure was slightly deformed when the content reached a certain degree.The fluorescence emission intensity of YBO₃:10%Eu³⁺/N-CQDs composites can be increased when the doping content of carbon quantum dots is within a certain range.Moreover,as the doping content of the carbon quantum dots increases gradually,the luminescence of the complex begins to change from red to white.Moreover,the doping content of carbon quantum dots gradually increased,and the luminescence of the composite began to change from red light to white light.PVA-YBO₃:10%Eu³⁺/N-CQDs composite film was prepared by reacting with polyvinyl alcohol（PVA）1799 as raw material using YBO₃:10%Eu³⁺/N-CQDs composite.The complex membrane is capable of fluorescence recognition of methamphetamine（MA）in solution.The PL spectroscopy results showed that methamphetamine（MA）solution had excellent quenching effect and good selectivity for the fluorescence of PVA-YBO₃:10%Eu³⁺/N-CQDs composite films.The MA solution concentration was in the range of 40-90μM showing a good linear relationship（R²=0.9922）,and the detection limit was 1.59μM.By testing samples in tap water,the recovery rate can reach 99.1-101.4%,and the relative standard deviation is 1.73-3.11%.Secondly,it was found that YBO₃:10%Eu³⁺/N-CQDs phosphor has a good performance in fingerprint recognition and can be well recognized on four different substrate materials.When the substrate was tin foil,multiple fingerprint detail feature points could be identified relatively clearly,and the fluorescent fingerprint image was still bright after several weeks of storage.