Preparation And Piezoelectric Catalytic Properties Of Perovskite-Based Nanomaterials

The rapid development of society has brought great economic benefits,but also a series of ecological and environmental problems.Water pollution,as a major environmental pollution,can be treated by various catalytic degradation technologies.Compared with traditional photocatalysis technology,piezoelectric catalysis uses the unique polarization property of piezoelectric materials to convert mechanical energy into chemical energy,and gets rid of the dependence on visible light.It is an ideal method with low energy consumption,wide application range and no secondary pollution.Based on this,Barium titanate（Ba Ti O₃）,a lead-free piezoelectric material,was selected as the research object in this paper to study the effect of morphology regulation,element doping and semiconductor composite on its piezoelectric catalytic performance.The main work of this paper is as follows:1.Preparation of Ba Ti O₃nanorods and piezoelectric catalytic propertiesThe Ba Ti O₃nanorods were prepared by microwave hydrothermal method,and the effects of precursor Ba/Ti ratio,reaction temperature and reaction time on the piezoelectric catalytic performance of Ba Ti O₃nanorods were studied.The change of process parameters will affect the morphology of Ba Ti O₃nanorods and the piezoelectric catalytic degradation performance of bati O3 nanorods.When Ba/Ti=5:1,reaction temperature 180℃and reaction time 90 min,the catalytic degradation performance of Ba Ti O₃nanorods is the best,and the degradation rate of Ba Ti O₃nanorods remains at 85%after four cycles of catalytic experiments,showing good stability and reusability.2.Preparation and piezoelectric catalytic performance of Ba_1-xCu_xTi O₃nanofibersBa_1-xCu_xTi O₃（x=0,0.01,0.02,0.03,0.04）nanofibers with different Ba/Cu ratios were prepared by hydrothermal method.The effect of Cu doping on the piezoelectric catalytic degradation of organic dyes by Ba Ti O₃nanofibers and its mechanism were studied.Under the excitation of ultrasonic vibration for 100 min,the piezoelectric catalytic activity of Ba_0.98Cu_0.02Ti O₃nano-fiber catalyst was the highest,and the degradation rate of Rhodamine B solution was 80.12%.Compared with the piezoelectric catalytic activity of pure Ba Ti O₃nanofiber catalyst,the degradation rate of Rhodamine B solution was increased by 47.92%by Ba_0.98Cu_0.02Ti O₃,and the doping of Cu element effectively increased the piezoelectric catalytic degradation rate of Ba Ti O₃nanofiber.Subsequent experiments showed that Ba_1-xCu_xTi O₃（x=0,0.01,0.02,0.03,0.04）nanofibers had good stability and universality,and the main active groups in the reaction process were·OH and·O₂^-.In addition,the experimental results show that both ultrasonic vibration and catalyst are necessary conditions for piezoelectric catalysis.Piezoelectric photocatalysis can further improve the effect of piezoelectric catalysis.3.Preparation of Ba Ti O₃/g-C₃N₄heterojunction and study of piezoelectric catalytic performanceBa Ti O₃/g-C₃N₄heterojunction was prepared by calcination,and the effect of different proportions of heterojunction on its piezoelectric catalytic performance was studied.With the increase of g-C₃N₄,the piezoelectric catalytic performance of the heterojunction increases first and then decreases.The degradation rate of 5%Ba Ti O₃/g-C₃N₄heterojunction is the best,reaching 70.3%,which is much higher than that of pure Ba Ti O₃57%.Because the interfacial electric field in the heterojunction can transport the vibration-separated carriers in time and accelerate the carrier migration,the piezoelectric catalytic performance of Ba Ti O₃/g-C₃N₄heterojunction can be significantly improved within a certain range.In addition,the Ba Ti O₃/g-C₃N₄heterojunction has certain universality,and the active groups·OH and·O₂^-play a major role in the catalytic degradation process.