Li Guanxing, Zhang Hui, Han Yu
Advanced Membranes and Porous Materials Center, Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Electron Microscopy Center, South China University of Technology, Guangzhou 510640, China.
Chem Rev. 2023 Sep 13;123(17):10728-10749. doi: 10.1021/acs.chemrev.3c00364. Epub 2023 Aug 29.
Phase engineering of nanomaterials (PEN) is an emerging field that aims to tailor the physicochemical properties of nanomaterials by precisely manipulating their crystal phases. To advance PEN effectively, it is vital to possess the capability of characterizing the structures and compositions of nanomaterials with precision. Transmission electron microscopy (TEM) is a versatile tool that combines reciprocal-space diffraction, real-space imaging, and spectroscopic techniques, allowing for comprehensive characterization with exceptional resolution in the domains of time, space, momentum, and, increasingly, even energy. In this Review, we first introduce the fundamental mechanisms behind various TEM-related techniques, along with their respective application scopes and limitations. Subsequently, we review notable applications of TEM in PEN research, including applications in fields such as metallic nanostructures, carbon allotropes, low-dimensional materials, and nanoporous materials. Specifically, we underscore its efficacy in phase identification, composition and chemical state analysis, observations of phase evolution, as well as the challenges encountered when dealing with beam-sensitive materials. Furthermore, we discuss the potential generation of artifacts during TEM imaging, particularly in scanning modes, and propose methods to minimize their occurrence. Finally, we offer our insights into the present state and future trends of this field, discussing emerging technologies including four-dimensional scanning TEM, three-dimensional atomic-resolution imaging, and electron microscopy automation while highlighting the significance and feasibility of these advancements.
纳米材料的相工程（PEN）是一个新兴领域，旨在通过精确控制纳米材料的晶相来调整其物理化学性质。为了有效地推进PEN，精确表征纳米材料的结构和组成的能力至关重要。透射电子显微镜（TEM）是一种多功能工具，它结合了倒易空间衍射、实空间成像和光谱技术，能够在时间、空间、动量以及越来越多的能量领域以极高的分辨率进行全面表征。在本综述中，我们首先介绍各种与TEM相关技术背后的基本机制，以及它们各自的应用范围和局限性。随后，我们回顾了TEM在PEN研究中的显著应用，包括在金属纳米结构、碳同素异形体、低维材料和纳米多孔材料等领域的应用。具体而言，我们强调了其在相识别、成分和化学状态分析、相演变观察以及处理对电子束敏感材料时遇到的挑战方面的功效。此外，我们讨论了TEM成像过程中，特别是在扫描模式下可能产生的伪像，并提出了尽量减少其出现的方法。最后，我们对该领域的现状和未来趋势发表见解，讨论包括四维扫描TEM、三维原子分辨率成像和电子显微镜自动化在内的新兴技术，同时强调这些进展的意义和可行性。
