Ge Meng, Yang Taimin, Wang Yanzhi, Carraro Francesco, Liang Weibin, Doonan Christian, Falcaro Paolo, Zheng Haoquan, Zou Xiaodong, Huang Zhehao
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-106 91, Sweden.
Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710119, China.
Faraday Discuss. 2021 Oct 15;231(0):66-80. doi: 10.1039/d1fd00020a.
Three-dimensional electron diffraction (3DED) has been proven as an effective and accurate method for structure determination of nano-sized crystals. In the past decade, the crystal structures of various new complex metal-organic frameworks (MOFs) have been revealed by 3DED, which has been the key to understand their properties. However, due to the design of transmission electron microscopes (TEMs), one drawback of 3DED experiments is the limited tilt range of goniometers, which often leads to incomplete 3DED data, particularly when the crystal symmetry is low. This drawback can be overcome by high throughput data collection using continuous rotation electron diffraction (cRED), where data from a large number of crystals can be collected and merged. Here, we investigate the effects of improving completeness on structural analysis of MOFs. We use ZIF-EC1, a zeolitic imidazolate framework (ZIF), as an example. ZIF-EC1 crystallizes in a monoclinic system with a plate-like morphology. cRED data of ZIF-EC1 with different completeness and resolution were analyzed. The data completeness increased to 92.0% by merging ten datasets. Although the structures could be solved from individual datasets with a completeness as low as 44.5% and refined to a high precision (better than 0.04 Å), we demonstrate that a high data completeness could improve the structural model, especially on the electrostatic potential map. We further discuss the strategy adopted during data merging. We also show that ZIF-EC1 doped with cobalt can act as an efficient electrocatalyst for oxygen reduction reactions.
三维电子衍射（3DED）已被证明是一种用于确定纳米晶体结构的有效且准确的方法。在过去十年中，各种新型复杂金属有机框架（MOF）的晶体结构已通过3DED得以揭示，这一直是理解其性质的关键。然而，由于透射电子显微镜（TEM）的设计，3DED实验的一个缺点是测角仪的倾斜范围有限，这常常导致3DED数据不完整，特别是当晶体对称性较低时。通过使用连续旋转电子衍射（cRED）进行高通量数据收集可以克服这一缺点，在这种方法中，可以收集并合并来自大量晶体的数据。在此，我们研究了提高数据完整性对MOF结构分析的影响。我们以沸石咪唑酯骨架（ZIF）ZIF-EC1为例。ZIF-EC1结晶于单斜晶系，具有板状形态。分析了具有不同完整性和分辨率的ZIF-EC1的cRED数据。通过合并十个数据集，数据完整性提高到了92.0%。尽管可以从完整性低至44.5%的单个数据集中解析出结构并精修至高精度（优于0.04 Å），但我们证明高数据完整性可以改善结构模型，特别是在静电势图方面。我们进一步讨论了数据合并过程中采用的策略。我们还表明，掺杂钴的ZIF-EC1可以作为氧还原反应的高效电催化剂。
