First-Principles Exploration for Electronic Structure and Optical Properties of S-Doped Bi4O5Br2

At present, many researches have explored the modification of Bi₄O₅Br₂, but relatively few have focused on non-metallic doping. Particularly, the effect of S doping on its photocatalytic mechanism remains unclear. Hence, this study systematically investigates the modulation mechanism of the electronic structure and optical properties of Bi₄O₅Br₂ by doped S using density functional theory (DFT) calculations. The calculated results indicate that the Br4Br1 model, in which S replaces Br at sites 4 and 1, is the most thermodynamically stable configuration. Comparing the models before and after doping, it is found that S doping significantly alters the lattice parameters of Bi₄O₅Br₂, thus affecting its electronic structure. Furthermore, differential charge density calculations reveal that S doping improves charge transfer capability and enhances the separation efficiency of photogenerated electron-hole pairs in Bi₄O₅Br₂. Calculated absorption spectra demonstrate that S doping augments the light absorption of Bi₄O₅Br₂ in the low and medium energy regions. Moreover, the dielectric function calculations further validate the effect of S doping on the optical properties of Bi₄O₅Br₂. Specifically, there is an increase in polarization and energy loss in the low energy region, with an opposite trend in the middle and high energy regions. Overall, S doping elevated the light absorption capacity and charge transfer efficiency of Bi₄O₅Br₂ by altering its lattice parameter and electronic structure, which facilitated the enhancement of photocatalytic performance. This study provides new insights into the development of efficient photocatalytic materials and broadens the potential of Bi₄O₅Br₂ for photocatalytic applications.