Design Of Iron-Modified Ceria Composite Photocatalyst Materials And Applications In Photocatalytic Degradation Of Acetaldehyde

In recent years,air pollution control has gradually attracted people’s attention,especially the removal of indoor toxic gases（such as formaldehyde,acetaldehyde,toluene and other volatile organic compounds）.Photocatalytic technology can oxidize and reduce toxic gases into non-toxic and harmless substances at room temperature,and it is widely used in the treatment of toxic and harmful gases with high concentration,large gas volume and strong stability.As a new type of photocatalyst,CeO2 has attracted the attention of many researchers.However,CeO2 has problems such as easy recombination of electron holes and low utilization of visible light in practical applications,which limits its wide application in the field of air pollution control.Therefore,in this paper,a series of physical and chemical methods were used to modify the structure,morphology and photocatalytic performance of ceria-based photocatalytic materials,and the relationship between the improvement of photocatalytic properties and the structure was deeply discussed.In the first part,in order to enhance the photocatalytic ability of CeO2 photocatalytic materials to degrade acetaldehyde,the authors tried selective deposition of Fe（Ⅲ）ions on the redox facets of CeO2,and explored the effect of Fe（Ⅲ）ions deposited on CeO2 with different morphologies.The experimental results show that the photo-oxidative degradation of CH3CHO by the product of Fe（Ⅲ）deposited on CeO2-r（named Fe/CeO2-r）is 4.71 times that of CeO2-r,which proves that when Fe（Ⅲ）ions are selectively photodeposited on CeO2（110）can enhance the photocatalytic oxidation of CH3CHO by CeO2.Through EPR analysis,Fe/CeO2-r will form a large number of active species ·O2-during the photocatalytic redox process,and the increase of the concentration of these active species will improve the efficiency of CeO2 photocatalytic hydrogen production.In the second part,in order to broaden the visible light absorption range of CeO2 samples,the effects of metal semiconductors（Fe2O3）combined with CeO2 with different morphologies on the photocatalytic degradation of acetaldehyde were investigated.The experimental results show that the Fe2O3/CeO2-r composite photocatalytic material has 4.05 times the photooxidative degradation ability of CH3CHO than CeO2-r.The enhanced photocatalytic performance is due to the direct band gap（about 2.3 eV）of Fe2O3,which facilitates better charge transfer between Fe2O3/CeO2 nanostructures.In addition,the recombination of CeO2 and Fe2O3 is conducive to the formation of a built-in electric field,which will accelerate the movement of photogenerated electron-holes to CeO2（Fe2O3）nanoparticles,thereby speeding up the transport speed of carriers and inhibiting the recombination of photogenerated electron-hole pairs.In the third part,in order to solve the problems of low specific surface area and less active sites of ceria-based composite photocatalytic materials,we tried to prepare ternary composite photocatalytic materials.The iron-based modified CeO2 was complexed with g-C3N4,and the experimental results display that Fe2O3/CeO2-r/g-C3N4 novel composite photocatalytic material has 3.64 times the photooxidative degradation ability of CH3CHO than CeO2-r.TEM,HR-TEM and other characterizations prove that the composites are better dispersed on the carbon nitride surface and may expose more reactive sites;the photocurrent,impedance and other experiments confirmed that the electron transport ability of the composite material was greatly improved after recombination with g-C3N4,which effectively enhanced the photocatalytic degradation of acetaldehyde.In general,this study achieved the improvement of the photocatalytic activity of CeO2-based composite photocatalytic materials for acetaldehyde degradation through the above three schemes.More meaningfully,a series of new and efficient ternary composite photocatalytic materials have been developed in this study,which have greatly improved the photocatalytic degradation activity of acetaldehyde under visible light conditions,and will show broad application prospects in the field of energy and environment.