Atomically Thin Graphene Windows That Enable High Contrast Electron Microscopy without a Specimen Vacuum Chamber

Subatomic species transport through atomically thin membranes: Present and future applications

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Revealing the Active Phase of Copper during the Electroreduction of CO2 in Aqueous Electrolyte by Correlating In Situ X-ray Spectroscopy and In Situ Electron Microscopy

The variation in the morphology and electronic structure of copper during the electroreduction of CO₂ into valuable hydrocarbons and alcohols was revealed by combining in situ surface- and bulk-sensitive X-ray spectroscopies with electrochemical scanning electron microscopy. These experiments proved that the electrified interface surface and near-surface are dominated by reduced copper. The selectivity to the formation of the key C-C bond is enhanced at higher cathodic potentials as a consequence of increased copper metallicity. In addition, the reduction of the copper oxide electrode and oxygen loss in the lattice reconstructs the electrode to yield a rougher surface with more uncoordinated sites, which controls the dissociation barrier of water and CO₂. Thus, according to these results, copper oxide species can only be stabilized kinetically under CO₂ reduction reaction conditions.

High-yield monolayer graphene grids for near-atomic resolution cryoelectron microscopy

Cryogenic electron microscopy (cryo-EM) has become one of the most powerful techniques to reveal the atomic structures and working mechanisms of biological macromolecules. New designs of the cryo-EM grids-aimed at preserving thin, uniform vitrified ice and improving protein adsorption-have been considered a promising approach to achieving higher resolution with the minimal amount of materials and data. Here, we describe a method for preparing graphene cryo-EM grids with up to 99% monolayer graphene coverage that allows for more than 70% grid squares for effective data acquisition with improved image quality and protein density. Using our graphene grids, we have achieved 2.6-Å resolution for streptavidin, with a molecular weight of 52 kDa, from 11,000 particles. Our graphene grids increase the density of examined soluble, membrane, and lipoproteins by at least 5-fold, affording the opportunity for structural investigation of challenging proteins which cannot be produced in large quantity. In addition, our method employs only simple tools that most structural biology laboratories can access. Moreover, this approach supports customized grid designs targeting specific proteins, owing to its broad compatibility with a variety of nanomaterials.

Atmospheric scanning electron microscopy and its applications for biological specimens

Scanning electron microscopy in ambient conditions (Air-SEM) was developed recently and has been used mainly for industrial applications. We assessed the potential application of Air-SEM for the analysis of biological tissues by using rat brain, kidney, human tooth, and bone. Hard tissues prepared by grinding and frozen sections were observed. Basic cytoarchitecture of bone and tooth was identified in the without heavy metal staining. Kidney tissue prepared using routine SEM methodology yielded images comparable to those of field emission (FE)-SEM. Sharpness was lower than that of FE-SEM, but foot process of podocytes was observed at high magnification. Air-SEM observation of semithin sections of kidney samples revealed glomerular basement membrane and podocyte processes, as seen using conventional SEM. Neuronal structures of soma, dendrites, axons, and synapses were clearly observed by Air-SEM with STEM detector and were comparable to conventional transmission electron microscopy images. Correlative light and electron microscopy observation of zebrafish embryos based on fluorescence microscopy and Air-SEM indicated the potential for a correlative approach. However, the image quality should be improved before becoming routine use in biomedical research.

Developing High-Performance Lithium Metal Anode in Liquid Electrolytes: Challenges and Progress

Lithium metal anodes are potentially key for next-generation energy-dense batteries because of the extremely high capacity and the ultralow redox potential. However, notorious safety concerns of Li metal in liquid electrolytes have significantly retarded its commercialization: on one hand, lithium metal morphological instabilities (LMI) can cause cell shorting and even explosion; on the other hand, breaking of the grown Li arms induces the so-called "dead Li"; furthermore, the continuous consumption of the liquid electrolyte and cycleable lithium also shortens cell life. The research community has been seeking new strategies to protect Li metal anodes and significant progress has been made in the last decade. Here, an overview of the fundamental understandings of solid electrolyte interphase (SEI) formation, conceptual models, and advanced real-time characterizations of LMI are presented. Instructed by the conceptual models, strategies including increasing the donatable fluorine concentration (DFC) in liquid to enrich LiF component in SEI, increasing salt concentration (ionic strength) and sacrificial electrolyte additives, building artificial SEI to boost self-healing of natural SEI, and 3D electrode frameworks to reduce current density and delay Sand's extinction are summarized. Practical challenges in competing with graphite and silicon anodes are outlined.