Preparation And Properties Of Tantalate Base Photocatalyst

With the advancement of global industrialization,the environmental pollution problem has become increasingly serious,which has become the main factor restricting economic development.How to solve the pollution problem in a green and efficient way has become a hot research direction.In the 1980s,perovskite-type NaTaO₃semiconductor material was found to degrade organic pollutants in water through redox reaction by absorbing the energy of ultraviolet light,which has a very broad application prospect.Since ultraviolet light only occupies a small part（≈7%）in the solar spectrum,this paper focuses on how to improve the photoresponse range and photocatalytic activity of NaTaO₃ catalyst,and synthesizes high-performance photocatalysts through the construction of heterojunction and multiple composite methods.The main contents are as follows:（1）The NaTaO₃-Ta₂O₅ composite catalyst was prepared by a hydrothermal method.It was found that Ta₂O₅ and NaTaO₃ had the most suitable ratio in the composite catalyst prepared at 160℃and 11 hours,and the degradation effect of rhodamine B under UV irradiation was the best.Then,NaTaO₃-Ta₂O₅/RGO composites were prepared by mechanical stirring using GO as raw material and ascorbic acid L-AA as reducing agent.We used SEM,XPS and other characterization methods showed that NaTaO₃-Ta₂O₅ was uniformly distributed on the surface of RGO,with a new Ta-O-C bond was formed.The degradation rate of Rhodamine B could reach 90%after 3 hours of visible light irradiation in the composite material with the amount of GO added at 3%wt.This is mainly attributed to the heterojunction structure of NaTaO₃-Ta₂O₅/RGO,which can reduce the band gap width and broaden the range of light response.Moreover,RGO can improve the migration rate of photogenerated electrons and further improve the photocatalytic performance.（2）Hexagonal Na YF₄:Yb³⁺,Tm³⁺upconversion nanoparticles（UCNPS）were prepared by a thermal decomposition method.UCNPS can absorb part of infrared light and convert it to visible light.By studying the preparation conditions,it was found that the up-conversion material had the highest fluorescence intensity when the reaction temperature was 330℃,the reaction time was 30 minutes,and the doping amount of Tm³⁺was 0.5%mol Na⁺.The NaTaO₃-Ta₂O₅/UCNPS@C composite was synthesized by hydrothermal method with glucose as raw material and citric acid as reducing agent.SEM,UV-Vis,PL,XPS and electrochemical analysis were used to prove that the carbon dots（CQDs）were uniformly distributed on the surface of NaTaO₃-Ta₂O₅/UCNPS composite material.The amount of glucose,citric acid and UCNPs were 360mg,90mg and 20mg,respectively,the reaction time was 12h,and the reaction temperature was180℃,the composite prepared had the best degradation effect.The degradation rate of rhodamine B reached 80%when the sunlight was exposed for 3h.The experiments of trapping agent showed that hole（h⁺）and hydroxyl radical（·OH）were the main active substances in the degradation reaction.The enhancement of photocatalytic effect is attributed to the fact that the introduction of CQDs is beneficial to the transfer of photogenerated electrons and inhibits electron-hole recombination in the semiconductor.At the same time,UCNPS can absorb part of the energy of infrared light,which is converted into visible light and absorbed by NaTaO₃-Ta₂O₅@C material,which broadens the light response range of the composite material.The synergistic effect of the three elements improves the photocatalytic activity of NaTaO₃.