Abstract
In situ transmission/scanning transmission electron microscopy (TEM/STEM) measurements have taken a central stage for establishing structure–chemistry–property relationship over the past ...couple of decades. The challenges for realizing ‘a lab-in-gap’, i.e. gap between the objective lens pole pieces, or ‘a lab-on-chip’, to be used to carry out experiments are being met through continuous instrumental developments. Commercially available TEM columns and sample holder, that have been modified for in situ experimentation, have contributed to uncover structural and chemical changes occurring in the sample when subjected to external stimulus such as temperature, pressure, radiation (photon, ions and electrons), environment (gas, liquid and magnetic or electrical field) or a combination thereof. Whereas atomic resolution images and spectroscopy data are being collected routinely using TEM/STEM, temporal resolution is limited to millisecond. On the other hand, better than femtosecond temporal resolution can be achieved using an ultrafast electron microscopy or dynamic TEM, but the spatial resolution is limited to sub-nanometers. In either case, in situ experiments generate large datasets that need to be transferred, stored and analyzed. The advent of artificial intelligence, especially machine learning platforms, is proving crucial to deal with this big data problem. Further developments are still needed in order to fully exploit our capability to understand, measure and control chemical and/or physical processes. We present the current state of instrumental and computational capabilities and discuss future possibilities.
Metal catalysts are of great importance in the modern chemical industry. It is well-known that the structures of metal catalysts determine their properties. However, recent studies suggested that the ...structures of metal catalysts change dynamically under reaction conditions, resulting in the deactivation or activation of metal catalysts. This Review summarizes the latest research progresses in the structural reconstruction of metal catalysts via controlled-atmosphere transmission electron microscopy. The state-of-the-art research technologies and crucial factors affecting the nanosized metal catalyst reconstruction are discussed. Various types of reconstruction phenomena are reviewed, including sintering and dispersion, reshaping, composition evolution, surface reconstruction of metal oxides, and strong metal–support interactions. Moreover, recent studies of the structure–property relationship of metal catalysts are also reviewed. Finally, we highlight current challenges and provide the perspectives for future research of this topic. We hope this Review provides insights for the rational design of high-performance metal catalysts.
Direct visualization of lead sulfide nanoparticle growth is demonstrated by selectively decomposing a chemical precursor from a multicomponent solution using in situ liquid transmission electron ...microscopy. We demonstrate reproducible control over growth mechanisms that dictate the final morphology of nanostructures while observing growth in real-time with subnanometer spatial resolution. Furthermore, while an intense electron beam can initiate nanoparticle growth, it is also shown that a laser can trigger the reaction independently of the imaging electrons.
Abstract Twinning, on par with dislocations, is critically required in plastic deformation of hexagonal close-packed crystals at low temperatures. In contrast to that in cubic-structured crystals, ...twinning in hexagonal close-packed crystals requires atomic shuffles in addition to shear. Though the twinning shear that is carried by twinning dislocations has been captured for decades, direct experimental observation of the atomic shuffles, especially when the shuffling mode is not unique and does not confine to the plane of shear, remains a formidable challenge to date. Here, by using in-situ transmission electron microscopy, we directly capture the atomic mechanism of the $$\left\{11\bar{2}1\right\}$$ 11 2 ¯ 1 twinning in hexagonal close packed rhenium nanocrystals. Results show that the $$\left\{11\bar{2}1\right\}$$ 11 2 ¯ 1 twinning is dominated by the ( b 1/2 , h 1/2 ) twinning disconnections. In contrast to conventional expectations, the atomic shuffles accompanying the twinning disconnections proceed on alternative basal planes along 1/6 $$\left\langle 1\bar{1}00\right\rangle$$ 1 1 ¯ 00 , which may be attributed to the free surface in nanocrystal samples, leading to a lack of mirror symmetry across the $$\left\{11\bar{2}1\right\}$$ 11 2 ¯ 1 twin boundary.
Although in sodium–oxygen (Na–O2) batteries show promise as high-energy storage systems, this technology is still the subject of intense fundamental research, owing to the complex reaction by which ...it operates. To understand the formation mechanism of the discharge product, sodium superoxide (NaO2), advanced experimental tools must be developed. Here we present for the first time the use of a Na–O2 microbattery using a liquid aprotic electrolyte coupled with fast imaging transmission electron microscopy to visualize, in real time, the mechanism of NaO2 nucleation/growth. We observe that the formation of NaO2 cubes during reduction occurs by a solution-mediated nucleation process. Furthermore, we unambiguously demonstrate that the subsequent oxidation of NaO2 of which little is known also proceeds via a solution mechanism. We also provide insight into the cell electrochemistry via the visualization of an outer shell of parasitic reaction product, formed through chemical reaction at the interface between the growing NaO2 cubes and the electrolyte, and suggest that this process is responsible for the poor cyclability of Na–O2 batteries. The assessment of the discharge–charge mechanistic in Na–O2 batteries through operando electrochemical transmission electron microscopy visualization should facilitate the development of this battery technology.
Localized corrosion of commercially pure Ti alloy (TA2) in 5 mmol/L NaF solution with pH = 3 was investigated by using scanning electron microscopy, focused ion beam and transmission electron ...microscopy techniques. Both micro-pits with low depth/diameter ratio (d/r = 0.25–1.0) and needle-like nano-pits with high d/r value (7.3) beneath the micro-pits are evident, indicating that corrosion of TA2 alloy in solution with fluoride ion is far away from “uniform”. Formation of needle-like nano-pits is attributed to its decreased pit repassivation ability. In addition, grain/twin boundaries have influences on the surface corrosion feature, while the scratches do not.
•Corrosion of TA2 alloy in 5 mmol/L NaF solution is far away from uniform.•Nanoscale corrosion pits with high d/r ratio found.•GB and TB influence corrosion feature while scratches do not.
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•Radiolabeled micro–sized liposomes can be used in RSO.•Simple and efficient liposome synthesis and radiolabeling is achieved.•High synovium retention rate is observed in rats for a ...prolonged period.•No observable leakage of 177Lu from the joints.•Low range of β particles associated with 177Lu is ideal for small joints.
Micro–sized multivesicular liposomes were prepared, radiolabeled with 177Lu, and tested in vitro and in vivo to evaluate the potential of 177Lu–labeled micro liposomes in radiosynoviorthesis (RSO) therapy. A standard reverse–phase procedure of liposome preparation with a lipid mixture of DPPC: CHOL (80:20%) was used for the synthesis. TEM and fluorescence microscopy imaging were performed to determine the size, shape, and structure of the prepared liposomes. Both measurements are in good agreement while TEM micrographs additionally indicate to a large multivesicular inner structure of prepared liposomes. A simple and straightforward procedure was used for liposome radiolabeling with 177Lu, a well–known and commonly used radionuclide in radiotherapy with favorable properties, that can be exploited in RSO therapy. Radiolabeled 177Lu–liposomes were tested in vitro for stability and then injected into the knee joints of Wistar rats where liposome in vivo behavior was followed up to 30 days post injection. Results from both ex vivo biodistribution and in vivo imaging studies presented a high stability and retention (>94 %ID) of 177Lu–micro liposomes in the synovial liquid for the entire observation period. Leakage of free 177Lu or 177Lu–liposomes from the synovial fluid has not been detected, indicating to a possible application of 177Lu–liposomes in radiosynoviorthesis (RSO) therapy.
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