密度泛函理论
X射线光电子能谱
光电子学
电子能带结构
作者
Jingnan Wang,Yuhong Huang,Jiaxin Guo,Jian-Min Zhang,Xiumei Wei,Fei Ma
标识
DOI:10.1016/j.jssc.2020.121181
摘要
Abstract 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.
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