First-principles Research Of BiVO₄-based Heterostructure Photocatalytic Splitting Of Water

The water splitting using solar energy to produce hydrogen is an important means to solve the energy problem,and efficient photocatalyst plays an important role in the process of water splitting.The low efficiency of photogenerated carrier separation and low conduction band position of BiVO₄ hinder its application in the field of photocatalytic water splitting.In order to solve the problem of low efficiency of water splitting by a single photocatalyst,based on the first principle,this paper constructs heterostructures with Janus two-dimensional material with asymmetric structure based on semiconductor photocatalyst BiVO₄.From the aspects of molecular dynamics and thermodynamics,the optical and electronic properties of monomers and heterostructures were calculated by VASP software,and the theoretical mechanism of water splitting of different heterostructures under visible light was studied,providing theoretical reference for semiconductor heterostructures to realize water splitting.The specific research contents are as follows:The MoSeTe/BiVO₄ and WSeTe/BiVO₄ heterostructures formed by contacting the Sesurface of MoSeTe and the Te surface of WSeTe with BiVO₄（010）have thermodynamic stability,and exhibit indirect band gaps of 1.43 e V and 1.54 e V,respectively.The light absorption ability is significantly enhanced in the visible light region.The results of differential charge and Bader charge analysis show that the built in electric field from Janus material to BiVO₄ is formed in the heterostructures,which meet direct Z-scheme mechanism.The existence of built in electric field can effectively realize the separation of photogenerated carriers.MoSeTe/BiVO₄ and WSeTe/BiVO₄ heterostructures can provide oxidation driving force of 1.95 e V and 1.76 e V,and reduction driving force of 0.40 e V and0.56 e V,respectively.WSSe/BiVO₄ and Mo SSe/BiVO₄ heterostructures formed by S-surface contact with BiVO₄ and Sesurface contact with BiVO₄ show the thermodynamic stability.The band gaps of these three heterostructures are 1.79 e V,1.81 e V and 1.37 e V,respectively.After forming the heterostructures,the light absorption capacity is significantly enhanced in the visible region and a built-in electric field is formed from the Janus material to BiVO₄,which meet the direct Z-scheme mechanism.These three heterostructures are able to provide oxidation driving forces of 1.54 e V,1.73 e V,and 1.99 e V,respectively,and reduction driving forces of 0.86 e V,0.56 e V,and 0.70 e V,respectively.These results show that the heterostructures constructed by BiVO₄ with several Janus materials show great potential for visible-light-driven water splitting.The Mo SSe/BiVO₄heterojunction formed by the contact between the Sesurface and BiVO₄ displays excellent visible light absorption ability,as well as both oxidizing-reducing capacity and carrier separation efficiency,which collectively contribute to its superior overall performance,demonstrating significant value for theoretical research in the field of photocatalytic water splitting.