Cryogenic TEM Research Articles

Cryogenic TEM for Soft-Hard and Liquid-Hard Interfaces in Nanotechnology and Energy Sciences

Cryogenic TEM for Soft-Hard and Liquid-Hard Interfaces in Nanotechnology and Energy Sciences

Ultra-Cold Cryogenic TEM Sample Holder with Liquid Helium and High Stability

Ultra-Cold Cryogenic TEM Sample Holder with Liquid Helium and High Stability

Visualizing Structure, Growth, and Dynamics of Li Dendrite in Batteries: From Atomic to Device Scales

AbstractThe growth of lithium (Li) dendrites, characterized by construction of internal Li substrate and surface solid electrolyte interphase (SEI), represents a significant hurdle for both liquid‐state and solid‐state Li batteries. To better understand the growth behaviors of these dendrites at atomic to device scale, advanced electron microscopy techniques have emerged as a valuable tool, providing high temporal and spatial resolutions for real‐time observations. In this review, the mechanistic aspects of growth of Li dendrites are delved first from both thermodynamic and kinetic perspectives. Then, a systematic overview of the state‐of‐the‐art in‐situ devices is provided that is developed for integration into electron microscopes, detailing the corresponding static and dynamic structures of Li dendrites. Additionally, the utilization of the non‐destructive cryogenic TEM technique is explored to classify and compare the local fine structure information of as‐formed Li deposits, which are influenced by various factors such as current density, temperature, electrolyte composition, solvents, and additives. Overall, this review article offers a comprehensive understanding of the physical origins associated with Li dendrites, spanning from atomic to device scales and encompassing both liquid and all‐solid‐state battery scenarios, then envisioning fundamental principles and strategies for optimizing batteries and overcoming the critical challenges posed by Li dendrites.

Cryogenic large volume 3D and TEM sample preparation with multiple ion species plasma FIB

Cryogenic large volume 3D and TEM sample preparation with multiple ion species plasma FIB

Cryogenic FIB and (S)TEM for Energy Storage and Conversion Materials Research.

Cryogenic FIB and (S)TEM for Energy Storage and Conversion Materials Research.

Semi-Automated EXLO for Ambient and Cryogenic TEM Specimen Manipulation.

Semi-Automated EXLO for Ambient and Cryogenic TEM Specimen Manipulation.

Cyanine Dye Coupling Mediates Self-assembly of a pH Sensitive Peptide into Novel 3D Architectures.

Synthetic multichromophore systems are of great importance in artificial light harvesting devices, organic optoelectronics, tumor imaging and therapy. Here, we introduce a promising strategy for the construction of self-assembled peptide templated dye stacks based on coupling of a de novo designed pH sensitive peptide with a cyanine dye Cy5 at its N-terminus. Microscopic techniques, in particular cryogenic TEM (cryo-TEM) and cryo-electron tomography technique (cryo-ET), reveal two types of highly ordered three-dimensional assembly structures on the micrometer scale. Unbranched compact layered rods are observed at pH 7.4 and two-dimensional membrane-like assemblies at pH 3.4, both species displaying spectral features of H-aggregates. Molecular dynamics simulations reveal that the coupling of Cy5 moieties promotes the formation of both ultrastructures, whereas the protonation states of acidic and basic amino acid side chains dictates their ultimate three-dimensional organization.

Cyanine Dye Coupling Mediates Self‐assembly of a pH Sensitive Peptide into Novel 3D Architectures

AbstractSynthetic multichromophore systems are of great importance in artificial light harvesting devices, organic optoelectronics, tumor imaging and therapy. Here, we introduce a promising strategy for the construction of self‐assembled peptide templated dye stacks based on coupling of a de novo designed pH sensitive peptide with a cyanine dye Cy5 at its N‐terminus. Microscopic techniques, in particular cryogenic TEM (cryo‐TEM) and cryo‐electron tomography technique (cryo‐ET), reveal two types of highly ordered three‐dimensional assembly structures on the micrometer scale. Unbranched compact layered rods are observed at pH 7.4 and two‐dimensional membrane‐like assemblies at pH 3.4, both species displaying spectral features of H‐aggregates. Molecular dynamics simulations reveal that the coupling of Cy5 moieties promotes the formation of both ultrastructures, whereas the protonation states of acidic and basic amino acid side chains dictates their ultimate three‐dimensional organization.

Hydrophobic, partially hydrophobic, and hydrophilic ZnO@SiO2 nanoparticles as fluorescent partitioning tracers for oil sensing applications

(a) Schematic representation of various functionalities on the surface of ZnO@SiO 2 nanoparticles. The partially hydrophobic (PH-NPs, S2), hydrophobic (HP-NPs, S3), and hydrophilic (H-NPs, S4) functionalities were developed on the surface of ZnO@SiO 2 NPs using various silanes having methyl, octyl, and amino groups, respectively. (b,c) The fluorescent NPs (S4) stayed entirely in the water phase due to the presence of –NH 2 group (hydrophilic nature), while the fluorescent NPs (S3) moved completely toward the oil phase due to the presence of octyl-group (hydrophobic nature) on their surface. However, the luminescent NPs (S2) were shifted toward the interface between two phases due to partially hydrophobic character ( CH 3 ) on their surface. • ZnO@SiO 2 NPs were synthesized via a modified sol–gel Stober protocol. • Surface functionalities were attained by co-condensation of various silanes. • Surface chemistry and partitioning behavior of ZnO@SiO 2 NPs were investigated. • ZnO@SiO 2 NPs have excellent fluorescence stability in aqueous environments. • Stability of ZnO@SiO 2 NPs was examined under harsh reservoir conditions. Fluorescent nano-tracers are being utilized for oil sensing applications in the reservoir. In this work, we developed various hydrophobic, partially hydrophobic, and hydrophilic zinc oxide encapsulated silica nanoparticles (ZnO@SiO 2 NPs) as smart nano-agents for oil sensing applications. The surface of ZnO@SiO 2 NPs was functionalized by co-condensation using various silanes in combination with tetraethyl orthosilicate (TEOS). Cryogenic TEM images display the average size of ZnO QDs (S0) and ZnO@SiO 2 nanoparticles (S1) around ∼5.3 nm and ∼50 nm, respectively. The surface chemistry and partitioning behavior of photoluminescent ZnO@SiO 2 NPs were investigated before and after mixing with the model oil under normal and UV light. The chemical and photoluminescence (PL) stability of ZnO@SiO 2 NPs was monitored in harsh reservoir conditions, such as variable temperature (30–100 °C) and high salinity (0–80 g L −1 ) environment. The results demonstrated that the surface modification and functionalization of these nano-agents with different functional groups (methyl, octyl) improved the nano-agents’ selectivity and stability after changing their hydrophilic-hydrophobic surface characters. This work is opening new research in the field of oil sensing, which promotes their potential utilization as cost-effective and efficient fluorescent tracer materials for the oil exploration industries.

Revealing the Structure and Properties of Polycrystalline Components of the Solid Electrolyte Interface

The formation, structure and composition of the solid-electrolyte interphase (SEI) in lithium batteries have been extensively explored in the prior literature. It is commonly accepted that the SEI consists of two inorganic layer followed by organic layer. However, very little is known about the actual grain boundary (GB) structure of the inorganic layer and the ions transport through it. The present work seeks to understand the structure and stability of the GBs formed between various inorganic components of the SEI and mechanisms of Li diffusion through them. The density functional theory (DFT) calculations supported by the high-resolution transmission electron microscopy (HRTEM) measurements are employed to understand the SEI GB atomic structures and their chemo-mechanical properties.DFT calculations were performed using the Vienna Ab Initio Simulations Package (VASP) code1 employing the generalized-gradient approximation (GGA) using the PBE (Perdew, Burke, and Ernzerhof)2 functional to account for the exchange-correlation effects. The Nudged Elastic Band (NEB) method3 is used for the Li migration barriers calculations as implemented in VASP. To build the GB structures, the Atomistic Tool Kit (ATK)4 “Interface Builder” tool is used, which allows to analyze all possible interphases between two slabs. Cryogenic TEM (Cryo-TEM) images are recorded on a JEOL ARM200CF TEM, equipped with a Gatan Oneview camera operated at 200 kV.The HRTEM measurements revealed the polycrystalline structure of the SEI inorganic layer consisting mainly of LiF, Li2CO3, Li2O and LiOH components. In addition, different surface orientations (e.g., 111, 200, 002, etc.) of the aforementioned components are identified. Based upon the HRTEM results (cf. Fig. 1 left-hand side), the corresponding computational slabs have been built as shown on the right-hand side in Fig. 1. After the optimization of all structures, Li adatom diffusion inside grain and GB and mechanical properties were calculated.For each GB, several Li adatom positions with multi-atom bonding were identified. The activation energy of Li diffusion varies significantly depending upon the slab’s structure and the number of Li adatoms. The NEB calculations also reveal a non-symmetric transition state for all considered structures, which indicates a complex multi-atom hopping mechanism. The calculated elastic properties show the decrease of Young’s modulus with an increase of Li adatoms. Our combined experimental and modeling findings provide valuable insights into developing mitigation strategies towards a better understanding of the SEI components stability and Li migration through the SEI.Figure 1. Identification of grain and GB of the SEI busing HRTEM (left) and the corresponding built DFT slab (right). Lavender spheres denote Li atoms, red spheres are the oxygen atoms, grey spheres represent carbon atoms and green spheres are F atoms. Blue sphere in the GB denotes Li adatom.References G. Kresse, Phys. Rev. B, 59, 1758–1775 (1999).J. P. Perdew, A. Ruzsinszky, G. I. Csonka, O. A. Vydrov, G. E. Scuseria, L. A. Constantin, X. Zhou, K. Burke, Phys. Rev. Lett., 100, 136406 (2007).G. Henkelman, B. P. Uberuaga, H. Jónsson, and G. Henkelman, J. Chem. Phys, 113 9901 (2020). Synopsys QuantumWise A/S, 2017/2. Figure 1

Evaluation of correlated studies using liquid cell and cryo-transmission electron microscopy: Hydration of calcium sulphate and the phase transformation pathways of bassanite to gypsum.

Insight into the nucleation, growth and phase transformations of calcium sulphate could improve the performance of construction materials, reduce scaling in industrial processes and aid understanding of its formation in the natural environment. Recent studies have suggested that the calcium sulphate pseudo polymorph, gypsum (CaSO4 ·2H2 O) can form in aqueous solution via a bassanite (CaSO4 ·0.5H2 O) intermediate. Some in situ experimental work has also suggested that the transformation of bassanite to gypsum can occur through an oriented assembly mechanism. In this work, we have exploited liquid cell transmission electron microscopy (LCTEM) to study the transformation of bassanite to gypsum in an undersaturated aqueous solution of calcium sulphate. This was benchmarked against cryogenic TEM (cryo-TEM) studies to validate internally the data obtained from the two microscopy techniques. When coupled with Raman spectroscopy, the real-time data generated by LCTEM, and structural data obtained from cryo-TEM show that bassanite can transform to gypsum via more than one pathway, the predominant one being dissolution/reprecipitation. Comparisons between LCTEM and cryo-TEM also show that the transformation is slower within the confined region of the liquid cell as compared to a bulk solution. This work highlights the important role of a correlated microscopy approach for the study of dynamic processes such as crystallisation from solution if we are to extract true mechanistic understanding.

Cryogenic TEM imaging of artificial light harvesting complexes outside equilibrium

The energy transport in natural light-harvesting complexes can be explored in laboratory conditions via self-assembled supramolecular structures. One such structure arises from the amphiphilic dye C8S3 molecules, which self-assemble in an aqueous medium to a double-wall cylindrical nanotube reminiscent of natural light-harvesting complexes found in green sulphur bacteria. In this paper, we report a way to investigate the structure of inner nanotubes (NTs) alone by dissolving the outer NTs in a microfluidic setting. The resulting thermodynamically unstable system was rapidly frozen, preventing the reassembly of the outer NT from the dissolved molecules, and imaged using cryogenic transmission electron microscopy (cryo-TEM). The experimental cryo-TEM images and the molecular structure were compared by simulating high-resolution TEM images, which were based on the molecular modelling of C8S3 NTs. We found that the inner NT with outer walls removed during the flash-dilution process had a similar size to the parent double-walled NTs. Moreover, no structural inhomogeneity was observed in the inner NT after flash-dilution. This opens up exciting possibilities for functionalisation of inner NTs before the reassembly of the outer NT occurs, which can be broadly extended to modify the intra-architecture of other self-assembled nanostructures.

Organic solution-phase transmission electron microscopy of copolymer nanoassembly morphology and dynamics

Direct imaging of the dynamics of polymeric assemblies in organic solvents is an outstanding challenge. Herein, we apply liquid cell transmission electron microscopy (LCTEM) to study polymeric nanomaterials in organic solvents. LCTEM is distinct from other TEM methods as it can be applied to characterize the morphology of nanomaterials in organic solvents. To enable this demonstration, we examined electron-solvent interactions for two common organic solvents, N,N-dimethylformamide and methanol, and compared these solvents to water. For each solvent, we developed Monte Carlo simulations and kinetic radiolysis models, providing scattering and chemical insight, respectively. Guided by theoretical results, we applied LCTEM and postmortem mass spectral imaging of poly(styrene)-b-poly(4-vinylpyridine) assemblies in each solvent. Then, a worm-to-micelle transformation in poly(styrene)-b-poly(4-vinylpyridine) was triggered via organic solvent mixing during LCTEM, enabling an experiment not possible through a cryogenic TEM time series. Our work provides a pathway for an expanded examination of nanomaterials in organic solvents via LCTEM, a neglected research area despite the obvious prevalence of such materials across chemistry and materials science.

Nucleic acid-based supramolecular structures: vesicular spherical nucleic acids from a non-phospholipid nucleolipid.

Vesicular spherical nucleic acids are dynamic nucleic acid-based supramolecular structures that are held together via non-covalent bonds. They have promising applications as drug and nucleic acid delivery materials, diagnostic and imaging tools and platforms for development of various therapeutic schemes. In this contribution, we report on vesicular spherical nucleic acids, constructed from a non-phospholipid nucleolipid – an original hybrid biomacromolecule, composed of a hydrophobic residue, resembling that of the naturally occurring phospholipids, and a DNA oligonucleotide strand. The nucleolipid was synthesized by coupling of dibenzocyclooctyne-functionalized oligonucleotide and azidated 1,3-dihexadecyloxy-propane-2-ol via an azide–alkyne click reaction. In aqueous solution it spontaneously self-associated into nanosized supramolecular structures, identified as unilamellar vesicles composed of a self-closed interdigitated bilayer. Vesicular structures were also formed upon intercalation of the nucleolipid via its lipid-mimetic residue in the phospholipid bilayer membrane of liposomes prepared from readily available and FDA-approved lipids (1,2-dipalmitoyl-rac-glycero-3-phosphocholine and cholesterol). The vesicular structures are thoroughly investigated by light scattering (dynamic, static, and electrophoretic) and cryogenic TEM and the physical characteristics, in particular, number of strands per particle, grafting density, and conformation of the strands, were compared to those of reference spherical nucleic acids. Finally, the vesicular structures were shown to exhibit cellular internalization with no need of transfection agents and enhanced colloidal and nuclease stability.

Twist-to-Untwist Evolution and Cation Polarization Behavior of Hybrid Halide Perovskite Nanoplatelets Revealed by Cryogenic Transmission Electron Microscopy.

Hybrid methylammonium lead iodide (MAPbI3) perovskite nanoplatelets (NPLs) have emerged as promising optoelectronic materials because of their remarkable properties in defect tolerance, band gap tunability, and light emission. However, the detailed formation mechanism, in particular the atomic structure information in the initial nucleation stage, stands as a mystery because of the intrinsic vulnerability toward moisture, electron beams, etc. By virtue of the imaging technique under the extremely low electron dose of the cryogenic TEM, atomic structures of MAPbI3 NPLs are imaged, and a twist-to-untwist structural evolution is captured. According to theoretical calculation results, the twist-to-untwist evolution is a spontaneous process, and the band gap will be reduced, which is further verified by the red shift of photoluminescence peaks with aging time. Moreover, MA cation polarization is observed by quantitative analysis of the atomic-resolution image of single-crystalline MAPbI3 NPLs, which demonstrates the high ion mobility in the lattice of the hybrid halide perovskites.

Liquid-Flowing Graphene Chip-Based High-Resolution Electron Microscopy.

The recent advances in liquid-phase transmission electron microscopy represent tremendous potential in many different fields and exciting new opportunities. However, achieving both high-resolution imaging and operando capabilities remain a significant challenge. This work suggests a novel in situ imaging platform of liquid-flowing graphene chip TEM (LFGC-TEM) equipped with graphene viewing windows and a liquid exchange system. The LFGCs are robust under high-pressure gradients and rapid liquid circulation in ranges covering the experimental conditions accessible with conventional thick SiNx chips. LFGC-TEM provides atomic resolution for colloidal nanoparticles and molecular-level information limits for unstained wet biomolecules and cells that are comparable to the resolutions achievable with solid-phase and cryogenic TEM, respectively. This imaging platform can provide an opportunity for live imaging of biological phenomena that is not yet achieved using any current methods.

Cathode-Electrolyte Interphase in Lithium Batteries Revealed by Cryogenic Electron Microscopy

Summary Cathode electrolyte interphase (CEI), the intimate coating layer formed on the positive electrode, has been thought to be critical. However, many aspects of CEI remain unclear. This originates from the lack of effective tools to characterize structural and chemical properties of these sensitive interphases at nanoscale. Here, we develop a protocol to preserve the native state and directly visualize the interface on the positive electrode using cryogenic electron microscopy. We find that under normal operation conditions, there does not exist an intimate coating layer at the single-particle level in carbonate-based electrolyte. However, upon brief external electrical shorting, a solid-electrolyte interphase, which usually forms on anodes, could form on cathodes and be electrochemically converted into a stable, conformal CEI in situ. The conformal CEI helps improve Coulombic efficiency and overall capacity retention of the battery. This generates a different perspective of CEI in commercial carbonate-based electrolytes than previously understood.

The Application of Cryogenic TEM for Studying Protein–Metal–Organic Frameworks

Journal Article The Application of Cryogenic TEM for Studying Protein–Metal–Organic Frameworks Get access Joesph Patterson Joesph Patterson University of California-Irvine, Irvine, California, United States Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 26, Issue S2, 1 August 2020, Pages 2010–2012, https://doi.org/10.1017/S1431927620020139 Published: 01 August 2020

Sweeping potential regulated structural and chemical evolution of solid-electrolyte interphase on Cu and Li as revealed by cryo-TEM

A fundamental understanding of solid-electrolyte interphase (SEI) is paramount importance for controlling the cycling performance of rechargeable lithium metal batteries. The structural and chemical evolution of SEI with respect to electrochemical operating condition remains barely established. Here we develop a unique method for imaging the evolution of SEI formed on the Cu foil under sweeping electrochemical potential. By using cryogenic TEM imaging combined with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy electronic structure analyses, we reveal that, for the vinylene carbonate (VC)-free electrolyte, the SEI formed at 1.0 V is a monolithic amorphous structure, which evolves to amorphous matrix embedded with Li 2 O particles as the voltage decreases to 0 V. In the case of VC-containing electrolyte, the SEI is featured by an amorphous matrix with Li 2 O particles from 1.0 V to 0 V. The thickness of SEI formed on Cu foil increases with decreasing voltage. Associated with the localized charge modulation by the surface topographic feature and defects in the Cu foil, the SEI layer shows direct spatial correlation with these structural defects in the Cu. In addition, upon Li deposition, the SEI formed on the Li metal has similar thickness with, but different composition from the SEI formed on the Cu foil at 0 V. Those results provide insight toward SEI engineering for enhanced cycling stability of Li metal. A fundamental understanding of solid-electrolyte interphase is paramount importance for controlling the cycling performance of rechargeable lithium metal batteries. Here we develop a unique method for imaging the evolution of SEI formed on the Cu foil under sweeping electrochemical potential. By using cryogenic TEM imaging combined with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy electronic structure analyses to directly probe the morphology, atomic structure, and chemical bonding of solid-electrolyte interphase formed on Cu and Li in the electrolyte without/with vinylene carbonate additive. We reveal that the vinylene carbonate additive is shown to significantly affect the solid electrolyte interphase on Cu at different potentials. Solid electrolyte interphases formed on Cu and Li show significantly different in chemical composition. • Developing a unique method for the formation of solid electrolyte interphase on Cu to facilitate cryo-TEM imaging. • Structural and chemical evolution of SEI formed on Cu with sweeping potentials were revealed by Cryo-TEM and XPS. • Vinylene carbonate additive is shown to significantly affect the solid electrolyte interphase on Cu at different potentials. • Solid electrolyte interphases formed on Cu and Li show significance difference in chemical composition.

Polarization-Modulated Bent-Core Liquid Crystal Thin Films without Layer Undulation.

Spatial confinement is known to affect molecular organizations of soft matter. We present an important manifestation of this statement for thin films of bent-core smectic liquid crystals. Prior freeze-fracture transmission electron microscopy (FFTEM) studies carried out on nitro-substituted bent-core mesogens (n-OPIMB-NO_{2}) revealed an undulated smectic layer structure with an undulation periodicity of ∼8 nm. We report cryogenic TEM measurements on ∼100 nm thick 8-OPIMB-NO_{2} films. In contrast to FFTEM results, our studies show only density modulation with periodicity b=16.2 nm, and no smectic layer undulation. We show that the discrepancy between the FFTEM and cryogenic transmission electron microscopy (cryo-TEM) results can be attributed to the different sample thicknesses used in the experiments. FFTEM monitors cracked surfaces of a relatively thick (5-10 μm) frozen sample, whereas cryo-TEM visualizes the volume of a thin (0.1 μm) film that was quenched from its partially fluid phase. These results have importance in possible photovoltaics and organic electronics applications where submicron thin films are used.