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Electron beam-induced polymerization (EBIP) has been widely explored in coatings, adhesives, and nanostructure fabrication, relying on electron irradiation to generate reactive species that initiate polymerization via radical pathways [1]. While its efficiency in solid and thin-film systems is well established [2], real-time observation of gas-phase polymerization at the nanoscale remains challenging due to the lack of suitable experimental platforms. In this study, we employ a custom-built ultrathin (UT) membrane gas-cell chip for in-situ closed-cell environmental transmission electron microscopy (ETEM). This platform offers enhanced reciprocal and spectral visibility, enabling precise tracking of crystallinity through diffraction patterns and gas composition through electron energy loss spectroscopy (EELS) [3-5]. By allowing real-time observation of polymerization kinetics under controlled electron irradiation, this work aims to elucidate the fundamental mechanisms governing EBIP in the gas phase, addressing a critical knowledge gap in electron beam-driven chemical reactions. 

2D nanomaterials have garnered significant attention due to their unique physicochemical properties. MXene, a type of twodimensional transition metal carbide, nitride, or carbonitride, has become a focal point in materials science due to its excellent metallic conductivity, tunable chemical functional groups, outstanding mechanical properties, and unique surface chemistry [1,2]. Compared to traditional metal oxides, MXenes exhibit superior mechanical strength and flexibility, making them ideal candidates for high-performance energy storage devices (such as lithium-ion batteries and supercapacitors) as well as flexible electronic devices [3]. However, there are still some limitations, such as the self-stacking phenomenon, which restricts the improvement of its performance. Researchers have gradually expanded various types of MXene structures, enhancing their value in fields such as energy, electronics, sensing, nanofluids, computing, and the environment by tuning the element composition, surface functional groups, interlayer structure, and composite structure design [4,5]. 

High-entropy metal-organic frameworks (HE-MOFs) offer a promising approach for advanced applications like energy storage, catalysis, and sensing, thanks to their high configurational entropy and synergistic effects from multiple elements. Despite the progress in synthesizing HE-MOFs, primarily through solvothermal methods, little is known about the reticular chemistry governing morphological variations. This work presents a new class of porphyrinic HE-MOFs, offering insights into the lattice transformations by controlling secondary building unit (SBU) topology. The study also explores spatial configuration and dynamic elemental composition, proposing that metal incorporation, spatial variation, and node stability are influenced by metal precursor dissociation and metal-oxygen bond strength, which dictate long-term structural dynamics. 

Environmental transmission electron microscopy (E-TEM) enables direct observation of nanoscale chemical processes crucial for catalysis and materials design. However, the high-energy electron probe can dramatically alter reaction pathways through radiolysis, the dissociation of molecules under electron beam irradiation. While extensively studied in liquid-cell TEM, the impact of radiolysis in gas phase reactions remains unexplored. Here, we present a numerical model elucidating radiation chemistry in both gas and liquid E-TEM environments. Our findings reveal that while gas phase E-TEM generates radiolytic species with lower reactivity than liquid phase systems, these species can accumulate to reaction-altering concentrations, particularly at elevated pressures. We validate our model through two case studies: the radiation-promoted oxidation of aluminum nanocubes and disproportionation of carbon monoxide. In both cases, increasing the electron beam dose rate directly accelerates their reaction kinetics, as demonstrated by enhanced AlOx growth and carbon deposition. Based on these insights, we establish practical guidelines for controlling radiolysis in closed-cell nanoreactors. This work not only resolves a fundamental challenge in electron microscopy but also advances our ability to rationally design materials with subÅngstrom resolution. 

Abstract Electrochemical CO₂reduction reaction (CO₂‐RR) in non‐aqueous electrolytes offers significant advantages over aqueous systems, as it boosts CO₂solubility and limits the formation of HCO₃⁻and CO₃²⁻anions. Metal–organic frameworks (MOFs) in non‐aqueous CO₂‐RR makes an attractive system for CO₂capture and conversion. However, the predominantly organic composition of MOFs limits their electrical conductivity and stability in electrocatalysis, where they suffer from electrolytic decomposition. In this work, electrically conductive and stable Zirconium (Zr)‐based porphyrin MOF, specifically PCN‐222, metalated with a single‐atom Cu has been explored, which serves as an efficient single‐atom catalyst (SAC) for CO₂‐RR. PCN‐ 222(Cu) demonstrates a substantial enhancement in redox activity due to the synergistic effect of the Zr matrix and the single‐atom Cu site, facilitating complete reduction of C₂species under non‐aqueous electrolytic conditions. The current densities achieved (≈100 mA cm⁻²) are 4–5 times higher than previously reported values for MOFs, with a faradaic efficiency of up to 40% for acetate production, along with other multivariate C₂products, which have never been achieved previously in non‐aqueous systems. Characterization using X‐ray and various spectroscopic techniques, reveals critical insights into the role of the Zr matrix and Cu sites in CO₂reduction, benchmarking PCN‐222(Cu) for MOF‐based SAC electrocatalysis. 

Polycrystalline ion conductors are widely used as solid electrolytes in energy storage technologies. However, they often exhibit poor ion transport across grain boundaries and pores. This work demonstrates that strategically tuning the mesoscale microstructures, including pore size, pore distribution, and chemical compositions of grain boundaries, can improve ion transport. Using LiTa₂PO₈as a case study, we have shown that the combination of LiF as a sintering agent with Hf⁴⁺implantation improves grain-grain contact, resulting in smaller, evenly distributed pores, reduced chemical contrast, and minimized nonconductive impurities. A suite of techniques has been used to decouple the effects of LiF and Hf⁴⁺. Specifically, LiF modifies particle shape and breaks large pores into smaller ones, while Hf⁴⁺addresses the chemical mismatches between grains and grain boundaries. Consequently, this approach achieves nearly two orders of magnitude improvement in ion conduction. Tuning mesoscale structures offers a cost-effective method for enhancing ion transport in polycrystalline systems and has notable implications for synthesizing high-performance ionic materials. 

Understanding chromatin organization requires integrating measurements of genome connectivity and physical structure. It is well established that cohesin is essential for TAD and loop connectivity features in Hi-C, but the corresponding change in physical structure has not been studied using electron microscopy. Pairing chromatin scanning transmission electron tomography with multiomic analysis and single-molecule localization microscopy, we study the role of cohesin in regulating the conformationally defined chromatin nanoscopic packing domains. Our results indicate that packing domains are not physical manifestation of TADs. Using electron microscopy, we found that only 20% of packing domains are lost upon RAD21 depletion. The effect of RAD21 depletion is restricted to small, poorly packed (nascent) packing domains. In addition, we present evidence that cohesin-mediated loop extrusion generates nascent domains that undergo maturation through nucleosome posttranslational modifications. Our results demonstrate that a 3D genomic structure, composed of packing domains, is generated through cohesin activity and nucleosome modifications.