Regulating electronic properties of BiOBr to enhance visible light response via 3d transition metals doping: DFT + U calculations

Abstract

In our work, the formation energies, band structures, densities of states, effective masses and optical absorption properties of pure BiOBr and 3d transition metals‐doped BiOBr have been calculated using DFT + U method. Ti, V, Fe, Cr, Co, Ni and Cu doping can induce impurity energy levels, originating from spin‐up or ‐down orbits of 3d transition metals (TMs), within the forbidden band of BiOBr, but Sc, Mn and Zn atoms only change the electronic delocalization in the valence band or conduction band region of BiOBr. Furthermore, with introduction of 3d TMs atoms, there exist the redshift phenomena for optical absorption band edge of BiOBr to different extents. The photo response priority order, structural stability and recombination probability of photoinduced carriers for 3d TMs‐doped BiOBr are summarized. Our theoretical findings should well explain the experimental observations in the previous literatures, and provide promising prediction and significant guidance for the well‐construction of BiOBr‐based photocatalyst systems.

BiOBr Micro–Nanosheets: Controllable Synthesis and Piezoelectric and Photoelectric Properties

“…17,18 In BiOBr, the valence band maximum (VBM) is mainly contributed by Br 4p and O 2p states whereas the conduction band maximum (CBM) differing in the k space value is mainly contributed by Bi 6p states with very less contribution of Bi 6s states, thereby primarily including the p−p transitions only. 19 In very recent reports, piezoelectric-like behavior was suggested in BiOBr to optimize the performance for photocatalysis by utilizing the piezocatalytic effect. 20 Under both illumination and external ultrasonic vibrations, the improved photocatalysis performance of BiOBr was attributed to the enhanced separation of the photogenerated electrons and holes due to the sustainable internal electric field developed by the piezoelectric-like behavior.…”

“…BiOBr with D 4h symmetry and the P 4 / nmm space group forms a PbFCl-type crystal structure with mono [Bi 2 O 2 ] 2+ and double [Br] − layers stacked together by the nonbonding van der Waals interaction arranged alternately along the c -axis. − The strong intralayer covalent bonding and weak interlayer van der Waals interaction along the [001] direction easily dissociates the BiOBr crystal in layered patterns with nonuniform distribution of charges. , In BiOBr, the valence band maximum (VBM) is mainly contributed by Br 4p and O 2p states whereas the conduction band maximum (CBM) differing in the k space value is mainly contributed by Bi 6p states with very less contribution of Bi 6s states, thereby primarily including the p–p transitions only …”