Metal Doped Titania/Zinc Oxide Photo-electro-catalytic Removal Of HCHO In Indoor Air

HCHO removal from indoor air was usually slow and inefficient due to the low concentration but persistent release,inadequate oxidation and less efficient catalysts at room temperature.Because photo-electro-catalysis was considered much more efficient in removing pollutants than photocatalysis and electro-catalysis alone,aqueous electrolytes are not usually considered in indoor air purification reactors and are rarely directly used for indoor air purification,therefore,in this thesis,the gas-liquid two-phase system is designed combing a semiconductor material supported on a stainless steel mesh as an air cathode,with an electrolyte anode,forming an air cathode photo-electro-catalytic system.The system removes formaldehyde in the air through photo-catalysis,electro-catalysis and photo-electro-catalysis respectively,among which PEC has a good degradation effect.The catalyst on the air cathode electrode in the system is Pt/TiO₂-ZnO,which is prepared by sol-gel method and chemical reduction method.The results of characterization of the material?XRD,SEM,TEM,XPS,CV,UV-vis,FTIR?show that the TiO₂ modified by Pt and ZnO broadens the absorption wavelength of the catalyst;due to the good electrochemical performance of Zn O and excellent performance of Pt,the composite material has very good electrochemical performance.The experimental results of EC,PC and PEC show that the degradation rate of PC is 44.21%when the mass fraction of Pt is 0.8%,the HCHO degradation rate of EC is 53%when the resistance is 400?,and the degradation rate of PEC is 74%when the resistance is 200?.The result of electrolyte optimization shows that the electrolyte has a high photo-electro-catalytic activity when it is 0.5 mol/L K₂SO₄.Through current comparison analysis:regardless of the size of the resistor,the current generated under the PEC system is higher than that produced by the EC system,and the lower the resistance,the greater the current.From the comparative analysis of degradation rates of EC,PC,and PEC,it was found that PC showed good activity in the early stage,and PEC showed very high activity in the later period and at a lower concentration.In the PEC system,the degradation rate is 65%when the doping amount of Fe⁰ is 5%,the degradation rate is 26%when the doping amount of Ni⁰ is 5%,Ni⁰-5%Fe⁰ when the doping amount of Ni⁰ is 1%.The degradation rate of the composite TiO₂-ZnO catalyst is 69%.Therefore,expensive Pt can be replaced by further optimization of these cheap metals.