Study On Fabrication Of Novel Bismuth Oxide Heterojunction Photocatalysts And Their Photocatalytic Activity Of Degrading Pollutants

With the acceleration of industrialization and urbanization process,people have been troubled by the problems of environmental pollution.As an efficient,green and potential technology,semiconductor photocatalysis technology has a broad application prospect in environmental purification.However,most photocatalysts still have shortcomings,such as narrow light response range and high recombination rate of photogenerated carriers,which limited the practical application.Bi-based photocatalysts is one of the most important photocatalytic materials that can be excited by visible light.As the simplest and most important bismuth compound,bismuth oxide has a strong application value in the field of photocatalysis.Therefore,we have constructed heterojunction based on Bi-based photocatalysts to enhance the separation efficiency of photogenerated electron and holes.Furthermore,we had studied the photocatalytic performance and mechanism of two heterojunction photocatalysts,respectively.The main research contents and conclusion are as follows:?1?Z-scheme MoO₃/Bi₂O₄ was prepared by hydrothermal method.SEM and TEM analysis confirmed that the tightly constructed heterostructures has formed between MoO₃ and Bi₂O₄,XPS analysis results further proved the formation of heterogeneous structures.The RhB was selected as the typical pollutant to evaluate the photocatalytic activity of as-synthesized MoO₃/Bi₂O₄ composites.The 15%MoO₃/Bi₂O₄ composite exhibited the best visible-light responsive photocatalytic activity for degrading rhodamine B?RhB?in aqueous solution,which is 2 times higher than the single phase Bi₂O₄.Meanwhile,15%MoO₃/Bi₂O₄ composite still keep good photocatalytic performance for degradation of RhB in aqueous solution after five recycles.·OH,·O₂^-and h⁺radicals are all involved in photocatalytic process,which were proved by trapping experiments.Furthermore,EIS and PL analysis results indicated that MoO₃/Bi₂O₄ heterojunction can effectively restrain the recombination of photogenerated electrons and holes and finally enhanced the photocatalytic activity.?2?Novel g-C₃N₄/Bi₂O_2.33 heterojunction photocatalyst was prepared by simple solvothermal method,and the phase composition,morphology,visible light absorption performance and the efficiency of photogenerated electron-hole separation of the photocatalysts were studied by various characterization methods.TC was selected as the target pollutant to evaluate the visible light photocatalytic performance of g-C₃N₄/Bi₂O_2.33.The photocatalytic degradation rate of TC about 40%g-C₃N₄/Bi₂O_2.33 is2.4 times and 6 times higher than pure g-C₃N₄ and Bi₂O_2.33,respectively.·O₂^-,h⁺,and·OH radicals are all involved in photocatalytic reactions,which were proved by trapping experiments.The enhanced photocatalytic activity of g-C₃N₄/Bi₂O_2.33 are attributed to two points:?1?The introduction of g-C₃N₄ broaden the visible light response range of the g-C₃N₄/Bi₂O_2.33 composites.?2?Heterojunction reduced the recombination rate of photogenerated carriers.In summary,this research based on bismuth oxide photocatalysts provides some references for the modification and mechanism research of bismuth oxide photocatalysts.