Abstract The electronic band structure, density of states, bond character and effective masses of hexagonal Bi9O7.5S6 crystal have been systematically investigated by applying first-principles calculations based on the density functional theory. Approving agreement between experimental and computational results for lattice parameters shows that the GGA-PBE method is suitable. Bi9O7.5S6 is an indirect band gap semiconductor with the value of 1.383eV using the GGA-PBE functional. The detailed analysis of Mulliken populations in Bi9O7.5S6 demonstrates the covalent nature orders for Bi1–S1, Bi2–O1(1), Bi2–O1(3) and Bi2–O2 bond are Bi1–S1>Bi2–O1(3)>Bi2–O2>Bi2–O1(1) on account of bond population values. More interestingly, the electron effective masses are larger in the interlayer direction than in the intralayer one, while the hole effective masses are lower in the interlayer direction than in the intralayer one. The photoinduced carriers for Bi9O7.5S6 have the high mobility that can be inferred from the effective masses of electron and hole in comparation with Bi2O3 and Bi2S3. The Bi9O7.5S6 is a strong photo-oxidation catalyst but the reduction power is limited in aqueous solutions.

中文翻译：

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六方Bi9O7.5S6的电子特性和有效质量：第一性原理计算

摘要 应用基于密度泛函理论的第一性原理计算，系统地研究了六方Bi9O7.5S6晶体的电子能带结构、态密度、键特性和有效质量。晶格参数的实验和计算结果之间的批准一致表明 GGA-PBE 方法是合适的。Bi9O7.5S6 是一种间接带隙半导体，具有 1.383eV 的值，使用 GGA-PBE 功能。Bi9O7.5S6中Mulliken种群的详细分析表明Bi1-S1、Bi2-O1(1)、Bi2-O1(3)和Bi2-O2键的共价性质顺序是Bi1-S1>Bi2-O1(3)> Bi2–O2>Bi2–O1(1) 考虑到债券总体价值。更有趣的是，层间方向的电子有效质量大于层内方向，而层间方向的空穴有效质量低于层内方向。与 Bi2O3 和 Bi2S3 相比，Bi9O7.5S6 的光生载流子具有高迁移率，可以从电子和空穴的有效质量推断出。Bi9O7.5S6 是一种强光氧化催化剂，但在水溶液中还原能力有限。