Study On Preparation Of ZnFe₂O₄/TiO₂ Composite Material And Its Photocatalytic Performance For NO_x Purification

With the rapid economic development,the gradual acceleration of the process of industrialization,the excessive use of fossil fuels and automobile exhaust will exacerbate environmental pollution and energy shortages.Among them,nitrogen oxides（NO_x）,as one of the common air pollutants,have great harm to the environment and the human body.NO_xcan cause acid rain and photochemical smog,and cause respiratory diseases and other diseases for human bodys.Compared with the concentration of nitrogen oxides produced by industrial production,the concentration of indoor nitrogen oxides is generally lower,and traditional methods are not suitable for treating low-concentration nitrogen oxides.As a new type of green technology,photocatalytic technology can effectively remove pollutants.As an excellent semiconductor material,TiO₂has a wide range of sources,good chemical stability,and is green and pollution-free,and is widely used in the field of photocatalysis.However,due to its wide band gap and weak absorption of visible light,it needs to be modified so that it can absorb visible light and degrade pollutants under visible light.Because TiO₂is not easy to use and collect,I compound it with magnetic materials and make it into paint that can be used in real life walls.In this paper,ZnFe₂O₄/TiO₂ binary composite materials with excellent photocatalytic activity,Fe₃O₄@ZnFe₂O₄/TiO₂ternary composite materials and ZnFe₂O₄/TiO₂/dm photocatalytic coatings were prepared by hydrothermal method and calcination method.XRD,SEM,TEM,In-situ DRIFTS and other characterization methods were used to analyze the prepared composite photocatalytic materials to study their photocatalytic performance and mechanism.（1）The ZnFe₂O₄/TiO₂ composite material was successfully prepared by a simple hydrothermal method.After many cycles of testing,it is found that the material has good stability and excellent performance.In addition,ZnFe₂O₄/TiO₂is easy to recycle due to its magnetic properties.The physical and chemical characterization of the catalyst by XRD,HRTEM and PL showed that the catalystforms a heterojunction at the interface,which can accelerate the charge transfer and improve the electron-hole separation efficiency,thereby improving the photocatalytic performance of the sample.After being compounded with ZnFe₂O₄,compared with TiO₂,its light response range has been significantly expanded,from ultraviolet absorption to visible light absorption.（2）It is stated that the loading of Fe₃O₄ can improve the photocatalytic activity of the catalyst,and there is a certain synergistic effect between Fe₃O₄and ZnFe₂O₄and does not affect the heterojunction effect between ZnFe₂O₄and TiO₂.Because Fe₃O₄is a basic oxide,it is also It can better adsorb NO and improve the photocatalytic activity.Finally,the addition of Fe₃O₄makes the magnetic properties have a certain enhancement,which can be better recycled.（3）Use the previously prepared ZnFe₂O₄/TiO₂ as raw material.The prepared ZnFe₂O₄/TiO₂binary composite photocatalytic material and the diatom mud paint are combined by stirring,ultrasonic and other physical methods to prepare a ZnFe₂O₄/TiO₂/diatom mud composite paint with high-efficiency photocatalytic properties.The performance of the coating is tested according to various national standards such as coating adhesion and water resistance,and its photocatalytic activity is evaluated with NO as the target.Among them,the photocatalytic material ZnFe₂O₄/TiO₂and the diatom mud ratio of 1:3,the drying temperature of 60℃photocatalytic diatom mud coating,the purification efficiency of NO after 5 cycles is still about 50%.