Modification Of LaFeO₃ Photocatalysis And Photo-Fenton Effect

LaFeO₃ is a perovskite-type oxide with good photoelectric properties and structural stability.In particular,the unique synergistic effect of LaFeO₃photocatalysis and photofenton has attracted much attention in the field of semiconductor photocatalysis.In this thesis,LaFeO₃nanoparticles with optical Fenton properties were prepared by the sol-gel method and combined with Bi OBr,Cu₂O,Au,rGO,CuS,etc.to form a multi-element heterojunction composite material.The samples were characterized by XRD,SEM,TEM,XPS,UV-vis DRS,PL,FTIR,EIS and transient photocurrent response.The photocatalysis and photofenton of the samples were analyzed by photocatalytic degradation of Rh B.The main research contents are as follows:（1）Prepare LaFeO₃nanoparticles with a size of about 30nm by sol-gel method,and use ion exchange method to uniformly compound LaFeO₃nanoparticles on Bi OBr assembled from thin sheets into flower-shaped Z-scheme heterojunction composite material LaFeO₃/Bi OBr.SEM and TEM showed that LaFeO₃nanoparticles with a diameter of 20-60 nm were attached to a smooth sheet with a diameter of 0.7-2.2μm and a thickness of 70-110 nm,forming a heterojunction composite material.Photocatalytic experiments under simulated sunlight show that 20%LaFeO₃/Bi OBr has the best photo Fenton and photocatalytic performances,which are 14.8 times and 1.7 times that of LaFeO₃and Bi OBr monomers,respectively.This is due to the Z-scheme heterojunction.The synergy of the charge transfer mechanism and the photo-Fenton process.The trapping agent experiment shows that the active groups in the photocatalytic degradation process include photo-generated holes,hydroxyl radicals and superoxide radicals,of which superoxide radicals play a major role.（2）LaFeO₃ particles are compounded to the surface of Cu₂O polyhedron by ion exchange method,and Au particles are deposited on the composite material by light reduction method,and finally the ternary composite material Au/LaFeO₃/Cu₂O is prepared.SEM and TEM show that Cu₂O is a regular polyhedron with a size of about 1-1.4μm,and two kinds of particles,LaFeO₃and Au,are uniformly compounded in Cu₂O.Au/LaFeO₃/Cu₂O heterojunction composites show higher photocatalytic activity and photo-Fenton activity than LaFeO₃and Cu₂O monomers,mainly due to the superior charge transfer mechanism,photo-Fenton effect and Au particles of the Z-scheme heterojunction Synergy.The active species trapping experiment was carried out,and the results showed that,among the holes,hydroxyl radicals and superoxide radicals,hydroxyl radicals play a major role.（3）LaFeO₃ and CuS nanoparticles are compounded on the bulk rGO through the co-precipitation method,and the use of rGO as a conductive medium can greatly improve the charge transfer and enhance the photocatalytic activity.Using XRD,ultraviolet-visible spectroscopy,scanning electron microscopy,transmission electron microscopy,XPS and infrared spectroscopy and other characterization techniques,the formation of the Z-scheme heterojunction material LaFeO₃/rGO/CuS was verified.In the process of degradation of methylene blue,methyl orange,rhodamine B and methyl orange/rhodamine B mixed solution under simulated ultraviolet light irradiation,the photocatalytic performance and photo-Fenton degradation activity of rGO/CuS/LaFeO₃composites are better than pure LaFeO₃,CuS and CuS/LaFeO₃,which may be related to the establishment of rGO and Z-scheme heterojunctions.rGO acts as a bridge between LaFeO₃and CuS for charge transfer and promotes the transport of photo-induced carriers.