The bismuth oxyhalide heterostructures BiOI/BiOX (X = F, Cl, Br) are systematically investigated under the framework of first principles by using the Heyd-Scuseria-Enrzerhof (HSE06) hybrid functional with the van der Waals (vdW) corrections. The calculated formation energies of BiOI/BiOX ensure the stable adsorption state of BiOX nanosheet on BiOI surface. The indirect band gaps of BiOCl, BiOBr and BiOI are 3.83 eV, 3.41 eV and 2.31 eV, while the direct band gaps of BiOF, BiOI/BiOF, BiOI/BiOCl and BiOI/BiOBr are 4.85 eV, 2.66 eV, 2.40 eV and 2.14 eV, respectively. Compared with the original host materials, the reduced band gaps of BiOI/BiOX heterostructures lead to a large transition of electrons from valence band (VB) to conduction band (CB) due to the incorporation of I-5p orbital in VB. The absorption edge of BiOI/BiOX has a red shift with respect to BiOX nanosheet, leading to effectively enhanced absorption in ultraviolet (UV) and visible (Vis) light range. The total and planar-averaged (along z direction) charge density difference, as well as band edge potentials demonstrate that the built-in electric field can effectively separate the photogenerated carriers and benefit the photocatalytic performances under Vis light irradiation.

通过使用范德华（vdW）校正的Heyd-Scuseria-Enrzerhof（HSE06）杂合功能，在第一原理的框架下系统地研究了卤氧化铋异结构BiOI / BiOX（X = F，Cl，Br）。BiOI / BiOX的计算形成能确保BiOX纳米片在BiOI表面上的稳定吸附状态。BiOCl，BiOBr和BiOI的间接带隙为3.83 eV，3.41 eV和2.31 eV，而BiOF，BiOI / BiOF，BiOI / BiOCl和BiOI / BiOBr的直接带隙为4.85 eV，2.66 eV，2.40 eV和2.14 eV分别。与原始主体材料相比，BiOI / BiOX异质结构的带隙减小导致电子从价带（VB）到导带（CB）的大跃迁，这是由于在VB中引入了I-5p轨道。BiOI / BiOX的吸收边缘相对于BiOX纳米片有红移，从而导致有效增强了紫外（UV）和可见（Vis）光范围内的吸收。总的和平面平均的（沿z方向）电荷密度差以及能带边缘电势表明，内置电场可以有效地分离光生载流子，并有利于可见光下的光催化性能。