Construction Of Heterojunction Photocatalyst And It’s Photocatalytic Performance

The issue of energy crisis is a permanent topic that is inseparable from the development of mankind,and it is related to all aspects of our lives.Through technical means,water can be decomposed into clean energy hydrogen.Among them,the photocatalytic water cracking technology can directly convert solar energy into hydrogen energy,which is more direct and simple.Since Fujishima et al.discovered in 1972 that Ti O₂was excited by ultraviolet light to produce hydrogen on the surface of the catalyst,researchers have paid more and more attention to photocatalytic hydrogen production.However,such photocatalysts generally have problems such as insufficient response to visible light and easy recombination of photogenerated electrons and holes,which affect their practical application in the field of photocatalytic hydrogen production.In response to this problem,this paper constructs WO₃/g-C₃N₄ heterojunction catalyst based on graphite-like phase carbon nitride（g-C₃N₄）and tungsten trioxide（WO₃）materials,and modifies it,which effectively promotes its simulation of visible light conditions Under the photocatalytic hydrogen production performance.The research content of this paper is as follows:（1）WO₃/g-C₃N₄ heterojunction catalyst was prepared by impregnation method.After WO₃ modification,the photocatalytic hydrogen production performance of g-C₃N₄ materials under simulated sunlight conditions can be significantly improved.The hydrogen production performance of the composite heterojunction is closely related to the loading of WO₃.According to the photocatalytic hydrogen production test,when the loading of WO₃ is 10 wt.%,the WO₃/g-C₃N₄ heterojunction catalyst has the best photocatalytic hydrogen production effect,and the hydrogen production rate is about 944μmol/（g·h）,compared with pure g-C₃N₄（hydrogen production rate is about 314μmol/（g·h））,the performance is improved three times.（2）A series of physical and chemical characterization methods were used to explore the photocatalytic hydrogen production reaction mechanism of WO₃/g-C₃N₄heterojunction catalyst.The analysis data shows that the prepared WO₃ has a nanorod structure,uniformly distributed on the surface of the layered g-C₃N₄,and the two have a larger contact area,effectively forming a WO₃/g-C₃N₄ heterojunction structure;WO₃ and g-C₃N₄ The recombination of C,N,O atoms changes the coordination environment of C,N,O atoms,and thus the visible light response of WO₃/g-C₃N₄composite catalyst is effectively improved through structural defects;WO₃/g-C₃N₄heterojunction recombination makes the energy band of the semiconductor dislocation recombination,Which effectively promotes the transport of photo-generated electrons and holes,inhibits the recombination of photo-generated carriers,and thus effectively improves the photocatalytic hydrogen production performance of the catalyst.