Study On The Preparation Of Ferrite Heterojunction Nanomaterials And Their Visible Light Photocatalytic Properties

With the development of scientific technology and the rapid growth of population,environmental pollution is becoming more and more serious.Photocatalytic oxidation technology can use natural solar energy to completely mineralize pollutants into carbon dioxide and water under normal temperature and pressure,which is a potential and effective way to deal with environmental problems.However,the utilization of visible light and catalytic activity are both low for the traditional Ti O₂catalyst.In order to solve these problems,three kinds of visible light responsive ferrite heterojunctions were constructed in this paper.The photocatalytic degradation rate can be improved because of the high efficiency of the separation and transport of photogenerated carriers existed in heterostructure.The morphology and structure of the heterojunction materials were characterized by modern instruments,and their photocatalytic activity for degrading toluene and antibiotics was investigated in detail.The main research results are as follows:（1）ZnFe₂O₄/WO₃tubular nano heterojunctions were prepared by solvothermal and solid grinding methods.A plenty of nano particles were adhered on the surface of nanotubes with the diameter of about 150 nm,and the nano heterojunctions had the characteristic peaks of X-ray diffraction and infrared belonged to ZnFe₂O₄and WO₃,respectively.Compared with pure WO₃,ZnFe₂O₄/WO₃heterojunction has higher catalytic activity.The degradation rate of toluene is 75.0%after being irradiated for 8 h,benzoic acid and benzaldehyde are the intermediate products,and CO₂is the final product.（2）ZnFe₂O₄/WO₃nanorod heterojunctions were successfully prepared,ZnFe₂O₄nanoparticles were evenly distributed on the surface of rod-like WO₃with a diameter of about200 nm and a length of about 500 nm.XRD and FTIR analysis results showed that the two materials were successfully combined.The degradation rate of metronidazole solution（100 mL,20 mg/L）reached 87.1%after 150 min of xenon lamp irradiation when 30 mg of ZnFe₂O₄/WO₃catalyst was added the pH was around 9.（3）BaFeO_2.5/g-C₃N₄nano heterojunction were prepared with 10%,30%and 50%mass percentage of g-C₃N₄.The micro morphology of the nanocomposites was sphere like with the diameter of about 30 nm and a fluffy surface,and the crystal structure and composition of the sample were further characterized by XRD and FTIR.The heterojunction material with 10% of g-C₃N₄has the highest catalytic activity,when the dosage is 20 mg,the degradation rate of cefixime solution（20 mg/L）reaches 87.9%after the photocatalytic reaction for 180 min.（4）The mechanism of visible light induced charge separation promoted by ferrite nano heterojunction is speculated as follows:based on the matched band structure of two single-phase semiconductors,the photogenerated electrons flow to the material with lower（5）conduction band position,while the photo generated holes move to the material with higher valence band position,which promotes the effective separation of photo generated charges,and thus improves the photocatalytic activity of ferrite heterojunction materials.