A Theoretical Study Of Electronic Structure And Interfacial Interaction In BiVO₄/WO₃ Heterostructure Semiconductor Material

With the rapid growth of the global economy,people’s demand for energy is increasing,and the environmental problems caused by traditional energy should not be neglected.Efficient use of solar energy can alleviate energy and environmental problems.Among the many ways to use solar energy to solve these problems,the photoelectrocatalysis is one of the most widely used and effective methods,and excellent electrode materials are the key to realize this process.In the related studies of photoanode materials,many previous studies have shown that common WO₃photoanode is non-toxic and has good electron transmission performance,while commonly used BiVO₄ photoanode has a moderate band gap and a relatively low cost.However,due to the high recombination rate of electron-hole pairs,their optical conversion efficiency is greatly limited.The photoanode of BiVO₄/WO₃heterostructure was constructed with WO₃ and BiVO₄,it can not only solve the problem of high recombination rate of electron-hole pairs,but also combine the excellent properties of BiVO₄ photoanode and WO₃ photoanode.Therefore,BiVO₄/WO₃ heterostructure photoanode is more favored than other semiconductor materials.A deep understanding of the photoexcited carrier separation mechanism of BiVO₄/WO₃ heterostructure is very important for improving the photocatalytic efficiency of BiVO₄/WO₃ heterostructure.However,most the experimental studies focused on the relationship between BiVO₄/WO₃ heterostructure material preparation method,morphology design,heteroatom doping and efficiency,etc.In addition,the performance of BiVO₄/WO₃ heterostructure is also affected by experimental interface engineering.In the experimental interface engineering environment,due to the presence of environmental pressure in the process of device preparation,the interfacial interaction in the form of strong interaction of bond class（binding）is bound to occur.However,the current experimental research based on BiVO₄/WO₃heterostructure surface is far from enough,and it is imperative to adopt powerful theoretical means to simulate and analyze the interfacial interaction and their influence at the atomic scale.In this study,the geometric stacking mode of BiVO₄/WO₃ heterostructure,as well as the relative distance between BiVO₄ surface and WO₃ surface were discussed firstly,the stability structure of BiVO₄/WO₃heterostructure was obtained,and two forms of interfacial interaction models were constructed,namely the van der Waals（vd W）model and the binding model.Then the electronic structure and optical properties as well as the band arrangement and charge transfer mechanism of the two interfacial interaction forms are described in detail.The results show that:（1）The valence band maximum and conduction band minimum of BiVO₄/WO₃heterostructure are mainly contributed by the 2p orbital of O atom in BiVO₄ and the5d orbital of W atom in WO₃,respectively.（2）The band arrangement of BiVO₄/WO₃heterostructure is a typical Type-II band arrangement,which is helpful for the spatial separation of carriers.（3）In the vd W structure and binding structure of BiVO₄/WO₃heterostructure,the electrostatic potential difference of BiVO₄ and WO₃ is different,which is 4.232 e V and 5.114 e V,respectively.（4）Compared with vd W model,the photogenerated electrons and holes are separated faster in the binding model.（5）The maximum effective electron accumulation in the binding structure of BiVO₄/WO₃heterostructure is more than 4 times that in the vd W structure.Combined with the calculation results in this paper and the formation conditions of non-harsh heterostructure materials,we believe that both the vd W form and binding form are coexisting interfacial interaction forms when extended to non-layered heterostructures.We hope that our work sheds light on exploring internal mechanisms and interfacial interaction in other heterostructure semiconductor materials,and also hope that the research content of this paper can provide new theories and new ideas for the design of heterostructure materials.