Interfacial Cohesive Interaction And Band Modulation Of Two-dimensional Graphene-based Heterostructure

The main work of this paper is to find and explore a kind of heterojunction photocatalyst composite based on graphene with stable configuration and high catalytic activity.The structure and properties of three heterojunction materials,MoS2/graphene,g-C₃N₄/graphene and BiPO₄/graphene,were investigated by first principles calculation and the conclusions can be available for reference.The effect of interfacial interaction on the charge distribution and the band edge potential of MoS₂/graphene heterojunction is studied by using the pwpp method based on dispersion correction,the study shows that the stable stack structure can be formed.Through the calculation of band structure,it is found that the coupling of MoS₂ and graphene leads to the conversion of MoS₂ to a n-type semiconductor and graphene into a p-type system with small bandgap.The electron density difference diagram is used to confirm that the internal electric field in the interface can inhibit the recombination of the photogenerated electron hole pair.The introduction of graphene can modulate the energy band of MoS₂ and shift its conduction band bottom potential to-0.31 eV,which improves the photoelectron reduction ability and facilitates the photocatalytic reduction reaction.The density functional theory is used to study the?-?stacking effect between the g-C₃N₄ and graphene sheets.This force changes the photoelectrochemical properties of g-C₃N₄.The energy band structure and work function of the calculated g-C₃N₄/graphene heterojunction indicate that these two materials are beneficial to the separation of photogenerated carriers,and also reduce the valence band top potential of g-C₃N₄ to enhance the photooxidation ability of the photogenerated holes.It is identified that the inhomogeneous onsite energies between interlayer and band edge modulations are induced by the inhomogeneous charge redistribution between interlayer caused by graphene.Further,the initial dynamic reaction process of oxygen atoms in g-C₃N₄/graphene heterojunction also confirms the significant role of graphene on the surface chemical reactions.The interfacial interaction and its effect on the charge distribution and the band edge potential of BiPO₄/graphene heterojunction are studied by using the pwpp method based on dispersion correction.The results show that a stable Van Der Waals heterostructure can be formed after the contact of BiPO₄?200?and graphene.The band structure calculation found that BiPO₄?200?coupled with graphene lead BiPO₄ as n-type semiconductors,graphene into p-type system of small band gap.the electronic density difference and the density of state diagram both prove that the internal electric field can inhibit the recombination of the photogenerated carriers.The introduction of graphene not only reduces the band gap of BiPO₄?200?,but also shifts the conduction band bottom potential to-1.84 eV,which improves the photoelectron reduction ability and facilitates the photocatalytic reduction reaction.