Preparation Of Tungsten Oxide-based Composite Films And Their Photocatalytic Reduction Of Cr(?)

WO₃ semiconductor photocatalyst is considered as one of the ideal photocatalyst materials.It has the following characteristics:green non-toxic,simple preparation,stable physical and chemical properties,sensitive to visible light,good electron transport performance,and cheap raw materials.In the gas detection,photocatalysis,optical switching devices and electrochromic devices and other fields have a wide range of applications.However,the rapid recombination of photogenerated electron-hole pairs in WO₃ also restricts its photocatalytic efficiency to some extent.Therefore,effectively inhibiting the photoelectron-hole pair recombination in WO₃ is an effective way to further increase the efficiency of WO₃ photocatalyst.Therefore,this article focuses on improving the performance of WO₃ thin-film photocatalyst materials.In this dissertation,WO₃ thin-film photocatalyst was the main research object.Hydrothermal method was used to introduce Fe element into WO₃ thin film.On this basis,g-C₃N₄ material was synthesized in situ to prepare WO₃,Fe-THWO₃ and Fe-THWO₃/g-C₃N₄ composite film material.The structure composition,surface morphology and properties of the sample were analyzed by various characterizations.The results showed that:?1?The Fe-doped WO₃ film prepared by hydrothermal method has higher photocatalytic activity than pure WO₃ film,which is equivalent to 5 times of the photocatalytic reduction of Cr???property of pure WO₃ film.The pure WO₃ is a triclinic phase and the doping of Fe element converts part of the triclinic WO₃ to hexagonal tungsten oxide.Therefore,there are both triclinic and hexagonal crystal phases in the WO₃ film samples doped with Fe.Since different crystal phases have different energy band structures,and the energy bands of the two crystal phases have extremely poor energy,WO₃ of the two crystal phases forms a heterojunction,and heterojunctions are generated,which promotes electrons and The separation of the hole pairs improves the separation efficiency of electron-hole pairs and further improves the photocatalytic reduction of Cr???.?2?Fe-THWO₃/g-C₃N₄ composite film was prepared by in-situ synthesis method,and the Fe-THWO₃/g-C₃N₄ composite film increases the performance of photocatalytic reduction of Cr???by about 10%over Fe-THWO₃.Fe-THWO₃ is an n-type semiconductor,and g-C₃N₄ is a p-type semiconductor.Since the two materials have different energy band structures and energy band positions,a p-n heterostructure is formed between Fe-THWO₃ and g-C₃N₄ materials.The formation of p-n heterostructures further enhances the separation of electron-hole pairs in the semiconductor and reduces the recombination of electron-hole pairs,thereby improving the separation efficiency of electron-hole pairs.In addition,the photocatalytic reduction of Cr???performance of the composite Fe-THWO₃/g-C₃N₄film was improved.