Band structure engineering is an effective way to improve the performance of photocatalysis. Herein, layered oxyhalides, BaBiOX (X = Cl, Br, and I), with single halogen layers were synthesized by using molten salt synthesis method. Density functional theory (DFT) calculation reveals that the valance band maximum (VBM) of BaBiOX mainly consists of O 2p orbitals, not halogen p orbitals (Cl-3, Br-4, and I-5), which means that this X1 oxyhalide owns the stability against self-degradation by photogenerated holes during the photocatalytic process. Simultaneously, with the increasing of atomic number from BaBiOCl to BaBiOI, the band gap () decreases from 3.523 eV to 2.777 eV. Eventually, BaBiOI exhibits the highest photocatalytic RhB degradation performance among all samples, mostly owning to the enhanced light absorption and improved separation and migration efficiency of photogenerated carriers. This study provides a new idea for designing bismuth-based photocatalysts by band engineering to solve environmental pollution.

中文翻译：

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单卤素层状 Sillén 卤氧化物 BaBiO2X（X = Cl、Br 和 I）的能带工程：孤对效应在光催化剂中的作用

能带结构工程是提高光催化性能的有效途径。在此，采用熔盐合成法合成了具有单卤素层的层状卤氧化物BaBiOX（X = Cl、Br和I）。密度泛函理论（DFT）计算表明BaBiOX的价带最大值（VBM）主要由O 2p轨道组成，而不是卤素p轨道（Cl-3、Br-4和I-5），这意味着该X1卤氧化物在光催化过程中具有抗光生空穴自降解的稳定性。同时，随着原子序数从BaBiOCl增加到BaBiOI，带隙()从3.523 eV减小到2.777 eV。最终，BaBiOI 在所有样品中表现出最高的光催化 RhB 降解性能，这主要归功于光吸收的增强以及光生载流子的分离和迁移效率的提高。该研究为通过能带工程设计铋基光催化剂解决环境污染提供了新思路。