Abstract α-MnS and γ-MnS photocatalysts were synthesized by the hydrothermal method and their size, structure, and appearance were determined by X-ray diffraction (XRD) patterns and scanning (SEM) and transition (TEM) electron microscopy images. α-MnS behaved as a bipyramid exposed with {2 0 0} facet, while γ-MnS behaved as a hexagonal prism exposed with {1 0 0}, {1 1 0}, and {1 0 2} facets. In addition, palladium (Pd)-modified γ-MnS photocatalysts were prepared via a photodeposition method, and their density of states and energy band structure were studied by theoretical calculations. The introduced Pd ions, which existed on the photocatalysts surface as –S–Pd–S– active species, expanded the visible light absorption, promoted the separation of electrons and holes, and improved the photocatalytic activity for the photoreduction of CO2 to CH4, indicating surface modification as an effective method for the development of MnS-based materials with high CO2 photoreduction activity. Therefore, this study could set the basis for the design and synthesis of novel visible light photocatalysts with active surface and high application potential in diverse fields.

中文翻译：

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在 CO2 光还原为 CH4 中具有增强光催化活性的钯改性 MnS 光催化剂的合成

摘要 采用水热法合成了 α-MnS 和 γ-MnS 光催化剂，并通过 X 射线衍射 (XRD) 图案和扫描 (SEM) 和跃迁 (TEM) 电子显微镜图像确定了它们的尺寸、结构和外观。α-MnS表现为暴露于{2 0 0}面的双锥体，而γ-MnS表现为暴露于{1 0 0}、{1 1 0}和{1 0 2}面的六棱柱。此外，通过光沉积法制备了钯（Pd）修饰的γ-MnS光催化剂，并通过理论计算研究了它们的态密度和能带结构。引入的 Pd 离子作为-S-Pd-S- 活性物质存在于光催化剂表面，扩大了可见光吸收，促进了电子和空穴的分离，提高了光催化 CO2 光还原为 CH4 的活性，表明表面改性是开发具有高 CO2 光还原活性的 MnS 基材料的有效方法。因此，该研究可为设计和合成具有活性表面和在不同领域具有高应用潜力的新型可见光光催化剂奠定基础。