Controllable Assembly Of Layered Rare Earth Hydroxide Nanomaterials And Their Application In Anti-counterfeiting

With the rapid development of commodity economy,the rampant phenomenon of fake and shoddy goods poses a great threat to consumers and the whole society.The development of high-level anti-counterfeiting strategy and encryption technology has become an important challenge in the field of information security and anti-counterfeiting.Rare earth luminescent materials have great application prospect in the field of information security and anti-counterfeiting because of their unique electronic,optical and chemical properties.However,traditional fluorescent materials are usually simple single-mode fluorescent materials with low security factor and easy to decipher,which can not meet the needs of anti-counterfeiting and information security storage.Therefore,the development of stimuli-responsive multi-mode fluorescent materials has become the development trend of new anti-counterfeiting materials in the future.The research focus of this paper is to develop a variety of stimuli-responsive multi-mode anti-counterfeiting new luminescence materials based on rare earth hydroxide.The main work is as follows:（1）The rare earth ions(Tb³⁺and Eu³⁺)were stabilized in the layered yttrium hydroxide host structure.Then,a dual-stimuli-responsive smart luminescence material based on Tb³⁺and Eu³⁺doped layered lanthanide hydroxide(LYH:Eu_xTb_1-xDPA)was developed by intercalating dipicolinic acid（DPA）through an anion exchange reaction.The material exhibits p H and temperature-dependent fluorescent properties,which can realize multiple encryption and decryption and anti-counterfeiting of confidential information.In addition,by adjusting the ratio of rare earth ions in the material,a series of multicolor phosphors can be obtained.The excellent color tunability makes it possible for LYH:Eu_xTb_1-xDPA to obtain latent fingerprints with excellent contrast and overall versatility in different environments.（2）Using rare earth ions,Ce,Tb-doped yttrium hydroxide fluoride nanotubes（YHF:Ce/5.7%Tb）as the matrix,EDTA-Eu complexes were modified on the surface to prepare DPA-stimulated nanotube composites.Based on the high-efficiency green fluorescence of the nanotubes themselves,the composite material can realize the change of emission color under the stimulation of DPA.When another external stimulus(Cu²⁺)is applied,the fluorescent color is restored.The results show that the nano-composite material can be used as security ink for information storage and anti-counterfeiting.（3）Yttrium hydroxide fluoride nanotubes doped with rare earth ions,Ce,Tb（YHF:Ce/11.4%Tb）as the carrier,upconversion nanoparticles Na YF₄:Yb/Tm were grown in situ,and then grafted with Cit-Eu-TC complexes to construct a triple-mode luminescent nanocomposite.The correct information can only be identified when the fluorescent color is completely correct under the illumination of the three excitation light sources,which increases the difficulty of counterfeiting.The results show that the material can be made into fluorescent ink and hydrogel to realize its application in the field of anti-counterfeiting.