Observation of formation and local structures of metal-organic layers via complementary electron microscopy techniques

Peng, Xiaoyuan; Pelz, Philipp; Zhang, Qiubo; Chen, Peican; Cao, Lingyun; Zhang, Yaqian; Liao, Hong‐Gang; Zheng, Haimei; Wang, Cheng; Sun, Shi‐Gang; Scott, Mary

doi:10.1038/s41467-022-32330-z

Cited by 22 publications

(30 citation statements)

References 62 publications

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“…In a recent study, Mary et al acquired 4D-STEM data on a Hf-based metal−organic layer material with a total electron dose of 800 e − /Å 2 . 72 Although this material is more stable than most MOFs, such a dose may have partially damaged its structure, which explains why only a 2.36 Å resolution was achieved in this study (Figure 2g). Another possible reason for not achieving atomic resolution is that the reconstruction algorithm (the SSB method) is not optimal.…”

Section: Discussionmentioning

confidence: 99%

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4D-STEM Ptychography for Electron-Beam-Sensitive Materials

Zhang

Han

2022

ACS Cent. Sci.

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Recent advances in high-speed pixelated electron detectors have substantially facilitated the implementation of four-dimensional scanning transmission electron microscopy (4D-STEM). A critical application of 4D-STEM is electron ptychography, which reveals the atomic structure of a specimen by reconstructing its transmission function from redundant convergent-beam electron diffraction patterns. Although 4D-STEM ptychography offers many advantages over conventional imaging modes, this emerging technique has not been fully applied to materials highly sensitive to electron beams. In this Outlook, we introduce the fundamentals of 4D-STEM ptychography, focusing on data collection and processing methods, and present the current applications of 4D-STEM ptychography in various materials. Next, we discuss the potential advantages of imaging electron-beam-sensitive materials using 4D-STEM ptychography and explore its feasibility by performing simulations and experiments on a zeolite material. The preliminary results demonstrate that, at the low electron dose required to preserve the zeolite structure, 4D-STEM ptychography can reliably provide higher resolution and greater tolerance to the specimen thickness and probe defocus as compared to existing imaging techniques. In the final section, we discuss the challenges and possible strategies to further reduce the electron dose for 4D-STEM ptychography. If successful, it will be a game-changer for imaging extremely sensitive materials, such as metal−organic frameworks, hybrid halide perovskites, and supramolecular crystals.

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Section: Discussionmentioning

confidence: 99%

Section: Applications Of 4d-stem Ptychographymentioning

confidence: 99%

4D-STEM Ptychography for Electron-Beam-Sensitive Materials

Zhang

Han

2022

ACS Cent. Sci.

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“…Apart from minimizing structural damage and improving electron tolerance during characterization, cryo-TEM also helps stabilize and preserve specimens at the status of interest during an in-situ TEM observation. Examples include in-situ studies on the crystallinity of MOFs in the liquid phase at specific reaction stages [45,46] and the construction of MOFs after interaction with gas species [47]. For the latter, two preferred adsorption sites for CO2 were discovered to be the centers within 6-ring channels and 4-ring channels, supported by HRTEM performed at -170 °C and with a cumulative electron flux of ~7 e -Å -2 using a DDEC camera.…”

Section: Cryo-temmentioning

confidence: 99%

“…The probe size was set to 2.5 Å, and the spatial resolution was 0.8 Å (Figure 4f,g) [85]. Cs-corrected HAADF-STEM images were able to visualize layer stackings and identify "missing clusters" defects, which are missing one and a row of clusters, respectively, in 2D Hf-MOFs [46]. Regarding the imaging of host-guest interactions, ADF-STEM mode with the beam current set to ≤10 pA revealed that the ALD approach was suitable for the uniform deposition of Pt nanoparticles into the pores of MIL-101(Cr) and there was no structural degradation during the loading process (Figure 5a,b) [84].…”

Section: Traditional Stem and Idpc-stemmentioning

confidence: 99%

Research Progress on Metal-Organic Frameworks by Advanced Transmission Electron Microscopy

Zheng¹,

Yin²,

Pan³

et al. 2023

Preprint

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Metal-organic frameworks (MOFs), composed of metal nodes and inorganic linkers are promising for a wide range of applications due to their unique periodic frameworks that can be flexibly tuned. Understanding of the structure-activity relationships can facilitate the development and application of MOFs nanomaterials. Transmission electron microscopy (TEM) is a one-of-a-kind technique capable of characterizing MOFs microstructures at the atomic scale. Besides, in-situ TEM set-ups make it possible to direct visualize the microstructural evolution of MOFs in real time, which enables monitoring transitions of MOFs during growth as well as under working conditions. However, MOFs are so sensitive to the high-energy electron beam which makes TEM-based characterizing methods challenging. In this review, we first introduce the main damage mechanisms for MOFs under electron beam irradiation and two strategies to minimize the damages: low-dose TEM and cryo-TEM. Then, we discuss the techniques combined with the two strategies to analyze the MOFs’ microstructure, including three-dimensional electron diffraction, direct detection electron counting camera, and iDPC-STEM. Groundbreaking milestones and research advances with respect to static characterization of MOFs structures are highlighted. In-situ TEM studies are exemplary reviewed to provide insights into MOFs dynamics induced by various stimuli. Additionally, perspectives on promising techniques that may further facilitate the MOFs study using TEM are analyzed.

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“…On the basis of two-dimensional (2D) coherent diffraction patterns acquired at 2D scan positions, which form the so-called 4D dataset, direct ptychographic methods [Wigner distribution deconvolution (WDD) or single side-band (SSB)] are highly dose efficient (28,29) and have the ability of live imaging (30,31). Both WDD and SSB are able to image beam-sensitive materials at higher contrast and spatial resolution (4,32,33). For example, an information limit of 2 Å has been demonstrated in zeolite with SSB (4).…”

Section: Introductionmentioning

confidence: 99%

Ptychographic measurements of varying size and shape along zeolite channels

Sha

Cui

et al. 2023

Sci. Adv.

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Sub-angstrom resolution imaging of porous materials like zeolites is important to reveal their structure-property relationships involved in ion exchange, molecule adsorption and separation, and catalysis. Using multislice electron ptychography, we successfully measured the atomic structure of zeolite at sub-angstrom lateral resolution for 100-nanometer-thick samples. Both lateral and depth deformations of the straight channels are mapped, showing the three-dimensional structural inhomogeneity and flexibility. Since most zeolites in industrial applications are usually tens to hundreds of nanometers thick, the sub-angstrom resolution imaging and accurate measurements of depth-dependent local structures with electron ptychography at low-dose condition will find wide applications in porous materials close to their industrially relevant conditions.

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Observation of formation and local structures of metal-organic layers via complementary electron microscopy techniques

Cited by 22 publications

References 62 publications

4D-STEM Ptychography for Electron-Beam-Sensitive Materials

4D-STEM Ptychography for Electron-Beam-Sensitive Materials

Research Progress on Metal-Organic Frameworks by Advanced Transmission Electron Microscopy

Ptychographic measurements of varying size and shape along zeolite channels

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