Semiconducting heterostructures are considered promising candidates for meeting specific environmental challenges, such as greener or decarbonated production of energy. However, optimizing the performance of these hybrid systems largely depends on the fine understanding of the mechanisms by which they are formed in relation to their mode of preparation. We report herein the synthesis of nanosized semiconducting heterostructures of ZnS@ZnO shell-core nature; this is from well-controlled preformed ZnO nanoparticles (NPs) modified via anion exchange process using (TMS)₂S. The formation of these ZnS@ZnO heterostructures has been investigated in depth, shedding light specifically on the sulfidation mechanism and its dynamics. Our study reveals the dynamic evolution of the nanomaterial in the sulfidation process, evidencing that it is both driven by the initial presence of oxygen vacancies─acting as gateways for sulfur atoms─and also by the action in the medium of (TMS)₂S, which as a sulfurizing agent behaves also as an oxygen atom extractor. The structural modification of the preformed monocrystalline ZnO nanomaterial into a polycrystalline ZnS hollow nanostructure occurs via amorphization–crystallization steps, which clearly depends on the amount of (TMS)₂S in the reaction. This morphological transition to a hollow structure has been followed by multinuclear NMR spectroscopy (¹H, ¹³C, ¹⁷O), and notably oxygen atoms at the interfaces of ZnS@ZnO heterostructures have been identified and quantified. Consistently, our study clearly establishes the link between the preparation mode of the ZnS@ZnO heterostructures and the modification of their optical band gaps as a function of their composition. The variation in optical properties, and the bowing of the band gap, depends on the sulfidation level, and this mode of sulfidation is clarified step-by-step by a DFT computational approach of surface and interface processes that is fully supported by the experimental characterization (XRD, WAXS, EDX line-analysis, HRTEM, STEM-HAADF) of these materials.

中文翻译：

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了解 ZnO 纳米晶体受控硫化合成 ZnSx@ZnO1–x 异质结构中的离子交换过程


半导体异质结构被认为是应对特定环境挑战的有前途的候选者，例如更环保或脱碳的能源生产。然而，优化这些混合系统的性能在很大程度上取决于对它们形成的机制与其制备模式相关的良好理解。我们在此报道了ZnS@ZnO壳核性质的纳米级半导体异质结构的合成;这是来自使用 （TMS）₂S 通过阴离子交换工艺修饰的受控预制 ZnO 纳米颗粒 （NP）。这些ZnS@ZnO异质结构的形成已经得到了深入的研究，特别是阐明了硫化机制及其动力学。我们的研究揭示了纳米材料在硫化过程中的动态演变，证明它既是由最初存在的氧空位（作为硫原子的门户）驱动的，也是由 （TMS）2 S 介质中的作用驱动的，TMS）₂S 作为硫化剂也充当氧原子萃取剂。预形成的单晶 ZnO 纳米材料的结构改性为多晶 ZnS 中空纳米结构是通过非晶化-结晶步骤发生的，这显然取决于反应中 （TMS）₂S 的量。这种形态转变为空心结构之后是多核 NMR 波谱 （¹H， ¹³C， ¹⁷O），值得注意的是，ZnS@ZnO异质结构界面处的氧原子已被识别和量化。始终如一，我们的研究清楚地建立了ZnS@ZnO异质结构的制备模式与其光学带隙的修改作为其组成的函数之间的联系。 光学特性的变化和带隙的弯曲取决于硫化水平，这种硫化模式通过表面和界面过程的 DFT 计算方法逐步阐明，该方法完全得到这些材料的实验表征（XRD、WAXS、EDX 线分析、HRTEM、STEM-HAADF）的完全支持。