Hydrothermal Synthesis Of Zinc Oxide Quantum Dots And Their Application In Information Encryption

As a new generation of semiconductor materials,zinc oxide quantum dots?ZnO QDs?not only exhibit excellent fluorescence characteristics under ultraviolet light,but also have many types of fluorescent colors,great spectral characteristics and stable photochemical properties.Furthermore,ZnO QDs have many advantages,such as very easy to form nanostructures,low production cost,non-biotoxicity,and environmental friendliness,etc.Therefore,ZnO QDs have been widely applied in bioimaging,photocatalysis,ultraviolet photodetectors,light-emitting diodes,solar cells,and gas sensors,etc.However,currently,the synthetic methods of ZnO QDs are still relatively cumbersome and time-consuming,and the applications of ZnO QDs are still limited.Therefore,it is still a challenge to find easier synthetic methods to meet the industrial needs of large-scale production,and how to extend the application of ZnO QDs is also a hot topic.In this thesis,we developed a simple method for hydrothermal synthesis of ZnO QDs,and the synthesized have been employed in information encryption,and the results of this thesis are list as follows:1.Zinc nitrate was converted to zinc nitrate hydroxide?Zn₅?OH?₈?NO₃?₂?sheets by dropping a small amount of oleylamine,then the Zn₅?OH?₈?NO₃?₂ was decomposed into fluorescent ZnO QDs under thermal condition.The critical conditions that Zn₅?OH?₈?NO₃?₂ begins to form ZnO QDs was studied,and the optimum conditions to synthesize fluorescent ZnO QDs have been determined.2.Information encryption has been realized from the ZnO QDs.Generally,different fluorescent materials are used as inks to write or print on the paper,which is only visible in certain illumination conditions or chemical conditions.Different from these,we used colorless and transparent zinc nitrate aqueous solution as ink and printed a certain pattern on copy paper,then sprayed the oleylamine alcohol solution onto the paper.The pattern will be encrypted at this stage.For decryption,the paper was heated at 120 ? for 1 minute,the encrypted pattern can be seen clearly under ultraviolet illumination.This method of encryption is quite easy and simple and provides a higher degree of encryption and anti-counterfeiting,which may inspire wide applications of ZnO QDs in the field of information encryption.