Gomes E O, Gracia L, Santiago A A G, Tranquilin R L, Motta F V, Amoresi R A C, Longo E, Bomio M R D, Andres J
Department of Analytical and Physical Chemistry, Universitat Jaume I, 12071 Castelló, Spain.
Phys Chem Chem Phys. 2020 Nov 18;22(44):25876-25891. doi: 10.1039/d0cp04596a.
In this work PbMoO4 and Pb1-2xCaxSrxMoO4 (x = 0.1, 0.2, 0.3, 0.4 and 0.5) solid solutions have been successfully prepared, for the first time, by a simple co-precipitation method and the as-synthesized samples were subjected to a water-based reflux treatment. Structural characterization of these samples was performed using X-ray diffraction with Rietveld refinement analysis and Raman spectroscopy. Their optical properties were investigated by UV-Vis absorption spectroscopy and PL emissions, and the photocatalytic activity of the as-synthesized samples for the degradation process of Rhodamine B has been demonstrated. The surface structure and morphologies were characterized by field emission scanning electron microscopy. To complement and rationalize the experimental results, the geometry, electronic structures, and morphologies of as-synthesized samples were characterized by first-principles quantum-mechanical calculations at the density functional theory level. By using Wulff construction, based on the values of the surface energies for the (001), (100), (110), (111), (011) and (112) surfaces, a complete map of the available morphologies for PbMoO4 was obtained and a good agreement between the experimental and theoretical predicted morphologies was found. The structural and electronic changes induced by the substitution of Pb by Ca and Sr allow us to find a relationship among morphology, the electron-transfer process at the exposed surfaces, optical properties, and photocatalytic activity. We believe that our results offer new insights regarding the local coordination of superficial Pb/Ca/Sr and Mo cations (i.e., clusters) on each exposed surface of the corresponding morphology, which dictate the photocatalytic activities of the as-synthesized samples, a field that has so far remained unexplored. The present study, which combines multiple experimental methods and first-principles calculations, provides a deep understanding of the local structures, bonding, morphologies, band gaps, and electronic and optical properties, and opens the door to exploit the electrical, optical and photocatalytic activity of this very promising family of materials.
在本工作中，首次通过简单的共沉淀法成功制备了PbMoO₄和Pb₁₋₂ₓCaₓSrₓMoO₄（x = 0.1、0.2、0.3、0.4和0.5）固溶体，并对合成后的样品进行了水基回流处理。使用X射线衍射结合Rietveld精修分析和拉曼光谱对这些样品进行了结构表征。通过紫外-可见吸收光谱和光致发光发射研究了它们的光学性质，并证明了合成后的样品对罗丹明B降解过程的光催化活性。用场发射扫描电子显微镜对表面结构和形貌进行了表征。为了补充并合理解释实验结果，在密度泛函理论水平上通过第一性原理量子力学计算对合成后样品的几何结构、电子结构和形貌进行了表征。通过使用基于(001)、(100)、(110)、(111)、(011)和(112)表面表面能值的Wulff构造，获得了PbMoO₄可用形貌的完整图谱，并发现实验预测形貌与理论预测形貌之间具有良好的一致性。Ca和Sr取代Pb所引起的结构和电子变化使我们能够找到形貌、暴露表面的电子转移过程、光学性质和光催化活性之间的关系。我们相信，我们的结果为相应形貌每个暴露表面上表面Pb/Ca/Sr和Mo阳离子（即团簇）的局部配位提供了新的见解，这些局部配位决定了合成后样品的光催化活性，而这一领域迄今为止仍未得到探索。本研究结合了多种实验方法和第一性原理计算，对局部结构、键合、形貌、带隙以及电子和光学性质有了深入理解，并为开发这类非常有前途的材料的电学、光学和光催化活性打开了大门。
