金属与二维热电材料定向复合结构的电子显微学研究

This project aims to reveal the microstructure evolution and interfacial configuration of several typical two dimensional thermoelectric materials (such as Sb2Te3 and Bi2Te3 nanoplates) with self-assembled metals (such as Ag and Cu) . Metals will be intentionally decorated on on the lateral sites of nanoplates. The microstructure will be characterized by employing various advanced transmission electron microscopy (TEM) techniques including the selected-area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), spherical aberration corrected scanning transmission electron microscopy (Cs-corrected STEM), and electron energy loss spectroscopy (EELS), etc.. Accompanied with the first-principles calculation and crystallographic simulation, we tend to fully gain the characteristics about the structure and composition evolution. Based on the first-hand information, the growth mechanism and interfacial configuration will be further evaluated. Our results will facilitate better understanding the relationship between the microstructure and thermoelectric performance, and thus serve as guidance for the future designing and optimizing of this kind of heterostructures.

拟选择几种用金属（Ag、Cu等)和二维热电材料（Sb2Te3、Bi2Te3等）的边缘复合的异质结构，利用先进的透射电子显微术，包括选区电子衍射、高分辨电子显微镜、X射线能量色散谱、球差校正透射电子显微镜和电子能量损失谱等，并配合必要的电子显微学模拟和第一性原理计算，从原子层次对此异质结构的物相、成份、缺陷、取向关系等进行充分表征，并在此基础上理解该异质结构的生长机制和界面构型。作为其他研究手段的很好补充，为设计和优化材料合成指引了方向，为深刻理解材料的微观结构与性能关系提供可靠的微结构依据。

独特的异质结构构造和界面微结构的研究一直是功能材料所关注的热点课题。在本项目中，我们可控合成了带孔的二维Bi2Te3纳米片，利用电子显微镜研究了纳米片和纳米孔随着反应温度和反应时间的结构演化过程，并在此基础上，将金属Cu颗粒定向复合在二维纳米片侧面，探索了该异质结构对材料热电性能的影响；另外，通过改变金属和基底的种类组合，研究了金属铂Pt与二维MoS2构建的异质结构及其在热处理条件下Pt原子随MoS2结构变化而发生的分布转变，并探讨了其在加氢脱氧反应中作用；此外，将Ti原子通过金属-载体强相互作用（SMSI）效应还原到Au纳米颗粒上，构造一定程度的包覆结构，利用电子能量损失谱技术的高空间分辨率以及对过渡金属表征的优势，结合热力学平衡模型，发现了SMSI在Au/TiO2体系中的粒径效应。