Controlling the morphological parameters of extended covalent organic frameworks remains challenging and represents an important yet often elusive metric of consideration. Typically, carbon nitride materials possess local ordering but remain largely amorphous in terms of their long-range order and orientation. This study probes the synthesis of a crystalline carbon nitride, poly(triazine imide) lithium bromide which possesses an atomically-precise extended structure, and demonstrates its exfoliation into a two-dimensional hexagonal sheet-like morphology. Furthermore, a previously unreported carbon nitride material, poly(triazine imide) copper bromide, or PTI-CuBr, was developed through an additional flux-assisted cation-exchange process and is shown to retain its internal Cu cations during solvothermal exfoliation. Characterization by dynamic light scattering and high-angle annular dark-field scanning electron microscopy reveals the morphological changes and captures the high aspect ratio of the thin carbon nitride sheets with <10 nm thickness while maintaining hundreds of nm in width. Additional characterization by energy-dispersive spectroscopy and X-ray photoelectron spectroscopy confirms that the Cu:Br:N molar ratio was maintained within the extended layers throughout the exfoliation process. This top-down synthesis approach differs from typical methods that isolate thin sheets for subsequent metal-cation coordination and illustrates the importance of maintaining oxygen-free conditions to minimize copper clustering. Thus, this new approach is demonstrated to provide a consistent and more homogeneous occupancy of the PTI pore spaces throughout the carbon nitride framework.

Al1-xScxN has attracted significant interest due to its large remnant polarization and low processing temperature when compared to other ferroelectric material systems. However, device dielectric failure before ferroelectric switching remains a critical limitation for AlScN-based memory devices. With the continuing trend toward device miniaturization, expanding the operating window is essential for next-generation memory development. In this work, we optimized the breakdown field (E-BD) and coercive field (E-C) in ultra-thin Al1-xScxN films by controlling defect density via adjustment of nitrogen process gas flow during sputter deposition. The characteristic breakdown field, E-BD, was evaluated using Weibull statistics, yielding optimal characteristic breakdown fields of 12.47 MV/cm (E-BD(+)) and-12.63 MV/cm (E-BD(-)) for samples deposited under 27.5 sccm N-2 flow. The minimum EC measured using 25 kHz bipolar triangular wave excitation was achieved for films deposited under a nitrogen flow of 25 sccm and increased for higher gas flows, a trend that is opposite to previous reports in much thicker films. The highest E-BD/E-C ratio of 2.25 was achieved in films deposited at 25 sccm N-2 flow, effectively expanding the operational window. The lowest imprint (0.32 MV/cm) obtained under low-frequency Capacitance-Electric Field scans was measured in films deposited under 30 sccm N-2 flow. Using a combination of X-ray diffraction and photoluminescence spectroscopy to study changes in crystal orientation and defects, device performance can be tuned by controlling the point defect concentration in the ultra-thin film via adjusting the sputtering N-2 process gas flow rate. A range of reactive gas flow from 25 to 30 sccm achieves high uniformity and the largest operational window, resulting in improved ferroelectric performance.

MXenes represent a promising class of 2D carbides, nitrides, and carbonitrides known for their high electrical conductivity, hydrophilicity, mechanical strength, and unique optoelectronic properties, which have led to numerous applications. However, their scalable synthesis in 1D morphology, such as nanotubes or scrolls, has not been demonstrated yet. This work presents a versatile and scalable method for manufacturing MXene scrolls, including Ti2CTx, Ti3C2Tx, Ti3CNTx, V2CTx, Nb2CTx, and Ta4C3Tx. We demonstrate a scalable and high-yield production up to 10 g of pure scrolls with precise control over their alignment and morphology. Properties of scrolls differ from 2D flakes; e.g., a freestanding film made of scrolled Nb2CTx presents 33 times increase in electrical conductivity and shows a superconducting state below 5.2 K. Films of MXene scrolls exhibit 3 times lower density and enhanced mass transport compared to flakes, resulting in an improved performance in supercapacitor electrodes and humidity sensors. The dispersion of the scrolls in water behaves like an electrorheological fluid. Aligning scrolls in an electric field allows for circuit switching between electrically insulating and conductive states. These scrolls can be assembled into vertically aligned MXene forests, fibers, and other architectures. The availability of 1D MXene scrolls offers exciting opportunities in many fields.

When a solid support undergoes crystallization, the advancing amorphous-to-crystalline transformation front separates regions of distinct surface energy, creating a moving interfacial energy boundary. A supported nanoparticle straddling such a boundary experiences an asymmetric particle-substrate interfacial energy environment that constitutes a lateral thermodynamic driving force for migration. Here, using in situ transmission electron microscopy to track Pt nanoparticle motion statistically, paired with time-resolved diffraction and 4D-STEM analysis to characterize support crystallization, we demonstrate that propagating crystallization fronts in amorphous AlO_x thin films actively drag supported Pt nanoparticles over long distances. Temporal correlation between the onsets of support crystallization and rapid particle migration, together with 4D-STEM virtual crystallinity maps, establishes that the front drives particle motion. Phase-field simulations confirm that particle-substrate interfacial energy contrast alone sustains particle drag, and identify curvature gradients along the particle surface as the mechanism by which the advancing front redistributes mass and displaces the particle. These results establish a general mechanism by which any propagating surface-energy boundary on a substrate can act as a deterministic driver of supported nanoparticle transport.

Kagome metals are an intriguing class of quantum materials as the presence of both flat bands and Dirac points provides access to functional properties present in strongly correlated and topological materials. To fully harness these electronic features, the ability to tune the Fermi level relative to the band positions is needed. Here, we explore the structural, electronic, and magnetic impacts of substitutional alloying within ferromagnetic kagome metal Fe3Sn2 in thin films grown by molecular beam epitaxy. Transition metals, Mn and Co, are chosen as substitutes for Fe to reduce or increase the d-band electron count, thereby moving the Fermi level accordingly. We find that Co is not incorporated into the Fe3Sn2 structure but instead results in a two-phase Fe–Co and (Fe,Co)Sn composite. In contrast, Fe3−xMnxSn2 films are realized with x of up to 1.0, retaining crystalline quality comparable with the parent phase. The incorporation of Mn repositions the flat bands relative to the Fermi level in a manner consistent with hole-doping, as revealed by hard x-ray photoemission and density functional theory. The Fe3−xMnxSn2 films retain room temperature ferromagnetism, with x-ray magnetic circular dichroism measurements confirming that the Fe and Mn moments are ferromagnetically aligned. The ability to hole-dope this magnetic kagome metal provides a platform for tuning properties, such as anomalous Hall and Nernst responses.

Characterizing lithium hydride (LiH) in lithium metal batteries is difficult: LiH is extremely air sensitive and composed of light elements that challenge conventional probes, leaving mesoscale morphology, and chemistry underexplored. We introduce a multifunctional cryogenic time-of-flight secondary ion mass spectrometry workflow that integrates top-view and cross-sectional analyses under temperatures below -145∘C. Using commercial LiH standards, the method identifies LiH via characteristic fragments  7Li1H-,  7Li1H2-,  7Li21H-, and  7Li21H+, and uses depth profiling to minimize surface contamination. Applied to lithium deposits electroplated on copper, cross-sectional mapping indicates that LiH is distributed throughout porous electrodes approximately 4μm thick, while top-view depth profiling resolves sub-nanometer composition gradients within the solid-electrolyte interphase. Complementary cryogenic scanning transmission electron microscopy and electron energy loss spectroscopy support the time-of-flight secondary ion mass spectrometry findings by showing LiH as thin surface-localized layers on individual lithium structures. The combined approach delivers chemically specific mapping across nanometer to micrometer length scales while preserving native states of highly reactive materials. This platform supports quantitative comparisons of spatial trends and strengthens multiscale analysis of complex battery interfaces and other air-sensitive systems.

Cryogenic electron microscopy (cryo-EM) has transformed structural biology by enabling near-atomic resolution imaging of macromolecules and the direct visualization of molecular architectures in native cellular environments. However, conventional cryo-EM, although outstanding at elucidating molecular density and morphology, provides little direct information about chemical composition or molecular state. Here, we review recent advances in scanning-based and spectroscopic electron microscopy that extend cryo-EM beyond phase contrast, including Z-contrast imaging, energy-dispersive X-ray spectroscopy, and electron energy-loss spectroscopy. We highlight how these techniques enable label-free mapping of elemental distributions and chemical states in beam-sensitive biological specimens, and we discuss emerging workflows that integrate spectroscopy with cryogenic sample preparation and correlative imaging. Together, these developments position spectroscopic cryo-EM as a powerful approach for linking structure, composition, and function across molecular and cellular scales.

Low noise sensors are needed to detect low-frequency, low-amplitude magnetic signals such as those produced by the heart. In this work, a multiferroic sensor composed of an FeGaB magnetostrictive layer and an AlN piezoelectric layer is used to demonstrate a novel strain-modulation technique which allows for the decoupling of the actuation and sensing frequencies. This sensor utilizes the fundamental length extensional mode to stress-modulate the FeGaB and the second harmonic length extensional mode to amplify and sense the modulated low-frequency magnetic field. This approach reduces the large electrical carrier signal which is associated with strain-modulated sensors by over 100 times. A noise spectral density of 10 nT/√Hz and 22 nT/√Hz is observed at 100 Hz and 1 Hz, respectively, for a device with an area of 0.13 mm2.

CMOS technology demands materials and architectures that emphasize low power consumption, particularlyforcomputations involving large-scale data processing and multivariable optimization. Ferroelectric materials offer solutions through enabling dual-purpose memory units that perform both storage and logic operations. In this study, we demonstrate ferroelectric field-effect transistors (FeFETs) with two-dimensional (2D) molybdenum disulfide (MoS2) channels fabricated on ultrathin 5-and 10-nm ferroelectric aluminum scandium nitride (Al1_xScxN). By decreasing the thickness of the ferroelectric film, we reduced the gate voltages (<3 V) required to switch the device conductance, enabling low-voltage operation. We observe a crossover in hysteresis behavior that varies with film thickness, channel fabrication method, and environmental conditions. Through an investigation of multiple parameters, including fabrication, scandium content, and dimensional scaling, we provide pathways to improve device performance.

The sluggish kinetics and insufficient durability of platinum-based catalysts remain crucial barriers limiting proton-exchange-membrane fuel cells (PEMFCs) deployment. Here, we report a theory-guided synthesis combined with rare-earth templating to realize a previously inaccessible Pt5Co-like phase with tailored atomic-scale strain. Guided by density functional theory (DFT) calculations, we identified that a Pt5Co-like sublayer can induce a unique mild compressive strain (-1.24%) to the Pt(111) shell and an optimal *OH binding energy shift (ΔE ≈ 0.11 eV). This shift positions the alloy catalyst near the apex of the oxygen reduction reaction activity volcano. This prediction guided the synthesis of ternary alloy Pt5(Ce)Co@Pt multilayer nanoparticles, featuring a Ce-stabilized core, a Pt5Co-like sublayer, and a Pt-rich shell. This catalyst demonstrates both exceptionally high activity and durability, achieving a mass activity of 2.6 A∙mgPt -1 in rotating disk electrode testing. In fuel cell membrane electrode assembly tests, Pt5(Ce)Co@Pt achieves a current density of 1.9 A∙cm-2 at 0.7 V under heavy-duty vehicle conditions. Remarkably, it maintains 1.2 A∙cm-2 after 1 80 000 AST cycles, doubling the U.S. DOE 2025 target. This work demonstrates a rational design strategy that DFT-guided strain engineering integrates with rare-earth templating to advance Pt-based catalysts for fuel cell applications.

We use in situ transmission electron microscopy with automated tracking to study supported gold nanoparticles (NPs) during high-temperature vacuum annealing. The average mass loss per NP is governed by a flat, nearly size-independent substrate-mediated evaporation profile. On top of this mean shrinkage, individual NPs show significant fluctuations in apparent growth or shrinkage, and NP volume follows a random-walk-like trajectory. To rationalize both the ensemble-mean behavior and the particle-resolved variability, we develop a self-consistent theory that couples substrate-mediated evaporation to collective 2D Ostwald-type mass exchange through a shared adatom field, described in terms of a renormalized screening length and background concentration. In the experimentally relevant regime, the theory predicts an approximately size-independent mean shrinkage rate and clarifies how net mass loss suppresses classical coarsening. Superimposed on this deterministic drift, we quantify stochastic volume trajectories and capture their fluctuation spectrum with a minimal Langevin description consistent with intermittent adatom attachment and detachment events. In addition, we characterize the lateral diffusive motion of NPs, which is responsible for their coalescence. Altogether, our results highlight that stochasticity is intrinsic at the nanoscale and that predicting the evolution of supported NPs at early and intermediate times requires a unified framework combining substrate-mediated evaporation, collective mass exchange, and stochastic fluctuations.

Ferroelectric AlScN is promising for CMOS-compatible non-volatile memory, but thickness scaling is limited by leakage, premature breakdown, and defect-mediated failure. Here we show that compositional grading within a continuous wurtzite AlN-AlScN lattice mitigates these limitations by distributing structural and polarization discontinuities across the film thickness, reducing defect formation and local field concentration. In a 20 nm graded heterostructure, monotonic Sc incorporation and AlN-rich boundaries produce reversible ferroelectric switching, an as-grown metal-polar state, a 21

The electrochemical CO2 reduction reaction (CO2RR) offers a promising approach for converting captured CO2 into valuable chemicals and fuels. However, CO2 streams from industrial sources often contain SO2 impurities, which compromise the performance and stability of many electrocatalysts. Herein, we report the impact of SO2 on immobilized single-atom transition-metal (TM) centerscobalt, nickel, and copper phthalocyanines (TM-PCs) on graphene. We show how the interaction between metal centers and SO2 impurities under CO2RR conditions affects the catalytic response. Among them, the Co-Pc/graphene catalyst demonstrates notable resistance to SO2 poisoning in membrane electrode assembly flow cells, while the other two TM-PCs deactivate. In situ X-ray absorption spectroscopy combined with density functional theory calculations indicates excellent structure stability of the Co-Pc/graphene catalyst and its favorable binding affinity for CO2RR intermediates over SO2-derived species. In contrast, both Cu-Pc/graphene and Ni-Pc/graphene catalysts exhibit severe degradation of the metal-N4 coordination structure and exhibit higher binding affinity toward SO2 species, leading to substantial activity loss in CO2RR. This work highlights the potential of tuning the metal centers of molecular catalysts to enhance impurity tolerance in electrochemical systems.

Abstract The vapor-phase synthesis can produce 2D transition metal carbides and nitrides (MXenes) from abundant precursors, bypassing MAX phase synthesis. However, little progress was made after the initial report by Talapin’s group on the chemical vapor deposition of MXenes on titanium foil, as the growth mechanisms remained poorly understood. Here, a scalable vapor-phase synthesis of high-quality Ti2CCl2 MXene from Ti, TiCl4, and CH4 is demonstrated, and the key features of the growth mechanism are elucidated. Increasing the Ti surface area while confining the reaction volume enables vapor-phase formation of Ti2CCl2 on quartz substrates. Supersaturation of TiCl2 increases gas-phase collision frequency, promoting nucleation and subsequent growth of 2D MXene flakes. The as-synthesized lamellae self-organize into spherulites with diverse morphologies, forming a porous nanocrystal network consistent with the gas-to-solid process. The continuous lateral growth into larger flakes is observed as synthesis time increases, suggesting the feasibility of wafer-scale synthesis. This study provides a practical synthesis route for Ti2CCl2 MXenes, accelerating MXene research and applications in quantum technology, optics, and electronics, where 2D crystals with low defect density are required.

Electron energy loss spectroscopy (EELS) has been established as a powerful analytical technique for investigating the oxidation state, band structure, and dielectric properties of materials with exceptional spatial resolution. Inspired by twisted 2D materials, we utilize low-loss EELS to examine the plasmonic excitations in 2D moiré Au nanocrystal superlattices (NCSLs) formed by liquid-air interface self-assembly using a double-dipping method. This approach produces stacked hexagonal layers that can be twisted, forming moiré patterns in NCSLs whose twist angles are precisely measured via scanning transmission electron microscopy (STEM). Low-loss EELS effectively mitigates challenges arising from fabrication-induced non-uniformity and reveals a blue shift in plasmonic excitation when comparing single-layer, double-layer, and twisted configurations. This sharply contrasts with the optical spectroscopy measurements, which show an overall red shift relative to the EELS data. The high spatial resolution of STEM-EELS further demonstrates that twist-induced symmetry breaking strongly influences plasmonic behavior. Coupled dipole modeling explains the observed discrepancies: the electron beam excites out-of-plane polarization modes unavailable to optical probes, while optical measurements average over ensembles. Our findings highlight that EELS provides complementary information to optical spectroscopy for understanding how structural arrangements at the nanoscale influence collective electronic properties, advancing the design of plasmonic metamaterials.

Understanding the real-time morphological evolution of nanoparticles under varying thermal and environmental conditions is crucial for revealing the mechanisms that govern their stability, growth, and functional performance in applications such as catalysis and nanomanufacturing. In-situ transmission electron microscopy provides direct, atomic-scale visualization of these dynamic processes through sequential imaging, capturing subtle transformations on a frame-by-frame basis. However, extracting reliable shape descriptors from such sequential image data remains challenging due to high noise, low contrast, inter-particle overlap, and the manual effort required for annotation. Existing segmentation methods often treat each frame independently, overlooking the temporal continuity inherent in in-situ imaging and failing to capture subtle but critical morphological transitions that underpin particle reshaping, coalescence, and structural evolution. To address these limitations, we present Swin U-Net Transformer with Temporal Convolutional Network for Segmentation (SwinTCN-Seg), a semi-supervised, spatiotemporally-aware framework that fuses transformer-based spatial encoding with temporal modeling to enable reliable analysis of morphological evolution in dynamic nanoparticle systems. Moreover, to reduce the need for dense manual labels, SwinTCN-Seg employs a pseudo-label propagation scheme that utilizes high-confidence predictions from labeled frames to guide learning on unlabeled ones, thereby uncovering transitional configurations. We validate SwinTCN-Seg on a large corpus of in-situ sequences of gold (Au) and platinum (Pt) nanoparticles imaged from 650 degrees C to 900 degrees C under vacuum and air environments. Despite being trained on only 5% of the labeled frames, the model achieves high segmentation accuracy, particularly in high-temperature regimes (>= 800 degrees C) where conventional methods struggle to detect complex phenomena such as faceting, sintering, and fragmentation. Code and models are available at https://github.com/kaur-manpreet325/TEM-Seg.

Ferroelectric aluminum scandium nitride (Al1-xScxN, AlScN) offers CMOS-compatible integration but suffers from high coercive fields and leakage currents that hinder thickness scaling. Further reduction in thickness is essential for low-voltage embedded nonvolatile memory applications. Boron incorporation into AlScN (AlBScN) suppresses leakage current in films down to 40 nm, yet its ferroelectric characteristics in ultrathin films remain unexplored. This letter demonstrates robust ferroelectric switching in 10 nm sputtered AlBScN capacitors with a low coercive field and approximately two orders of magnitude lower leakage than AlScN. Notably, the coercive field (E-c) extracted from capacitance-voltage measurements was 2.3 MV/cm, and the onset of symmetric polarization reversal was observed near 4.6 MV/cm in positive-up-negative-down (POND) measurements using 2 & micro;s pulses. Moreover, the breakdown field (EBD) was determined to be 10.0 MV/cm for 10 & micro;m diameter capacitors, suggesting a substantial margin between E-BD and E-c for reliable operation. These findings demonstrate AlBScN as a promising candidate for CMOS back-end-of-line (BEOL) compatible ferroelectric applications with reduced energy consumption and leakage current.

Bioinspired hierarchical microstructures offer a route toward engineered fatigue resistance in additively manufactured alloys. However, it remains unclear how discrete structural constituents independently govern damage accumulation, particularly during the critical fatigue initiation regime where short cracks strongly interact with local microstructure. Here, we investigate multiscale fatigue initiation in a dual-phase, nanolamellar AlCoCrFeNi2.1 high-entropy alloy. By comparing microscale specimens that isolate the nanolamellar structure against macroscale specimens containing the full melt-pool architecture, we identify size-dependent fatigue initiation mechanisms. We find that failure is dictated by nanolamellar interfaces at the microscale, whereas mesoscale melt pool boundaries serve to initiate fatigue at the macroscale. This mechanistic shift is accompanied by a transition from macroscale quasi-brittle failure to microscale plasticity-driven crack extension. Our results provide a physical framework for understanding how structural hierarchy governs the transition from discrete microstructural deformation to continuum fatigue fracture behavior, informing the design of damage-tolerant, additively manufactured alloys.

Carbon-nitride materials represent light-absorbing structures composed of earth-abundant elements capable of being leveraged for semiconductor photocatalysis at their surfaces. This study systematically investigates the addition of molecular modifiers to the synthesis of crystalline carbon nitrides to assess their effects on the materials' structure, optical bandgap, and photocatalytic activity for hydrogen (H2) and oxygen (O2) evolution under ultraviolet and visible-light irradiation. Melamine and five pyrimidine-centered analogs were employed as building blocks to modify various heteroatoms within the polymeric framework. The modified materials were characterized with attention to the differences introduced by the monomeric modifiers and their influence on the resulting structures and compositions. The findings indicate that these changes significantly broaden the visible-light absorption range, albeit with the gradual loss of the bulk crystalline structure. As the loading of modifiers increased beyond 50%, a predominantly amorphous form of carbon nitride emerged. XPS, 13C solid-state NMR, and SEM analyses corroborated the changes, which were attributed to modifications of the elemental composition and a reduced amount of Li cations and charge-balancing Cl anions owing to fewer binding sites in the intralayer cavities. In photocatalytic measurements under an ultraviolet 390 nm LED, and aided by photodeposited nanoparticle cocatalysts, the unmodified PTI-LiCl framework demonstrated the highest H2 evolution rate (HER; 3.44 mmolg-1h-1) with an apparent quantum yield of 5.4%, along with total water splitting at rates of 163 mu mol of H2g-1h-1 and 75.6 mu molO2 g-1h-1. While PTI-LiCl showed trace activity under a visible-light 440 nm LED, all modified materials exhibited enhanced reactivity with as low as 5% molecular modifiers. The photocatalytic rates peaked at a 15% modification level when using 2,4,6-triaminopyrimidine, with rates of 33 mu molg-1h-1 for HER, along with 19.7 mu mol of H2g-1h-1 and 8.7 mu mol of O2g-1h-1 for total water splitting. Density functional theory calculations were used to probe electronic structure changes resulting from the modifications. Thus, these results elucidate the structural, optical, and electronic changes arising from the five selected molecular modifiers and their impact on the semiconductors' photocatalytic properties.

The escalating demands of industrialization and development underscore the necessity for an efficient and scalable carbon capture and storage (CCS) methodology. Mineral carbonation of MgO presents itself as a promising solution due to its considerable theoretical capacity for CO2 adsorption. However, the sluggish kinetics of the carbonation process pose a significant challenge. Consequently, a comprehensive understanding of the structural and chemical alterations occurring during carbonation is imperative for material design. In this study, we conduct a thorough structural and chemical investigation of the MgO (sourced from different mine tailings) carbonation process using electron microscopic techniques. Our findings demonstrate that treating MgO with polar solvents enhances its degree of carbonation significantly, offering a promising avenue for improvement. Moreover, we observe a particle size dependency in MgO carbonation and note that the inclusion of additional materials, such as Si-based compounds, further accelerates the carbonation. Density functional theory (DFT) calculations provide insight into surface functionalization as a result of solvent treatment and its mechanistic effect on the origin of the enhanced carbonation of polar solvent-treated MgO, revealing a stronger interaction between CO2 and the treated MgO (100) surface as compared to the non-polar solvent treated surfaces. These discoveries showcase an alternative approach for enhancing MgO carbonation, thereby offering a potential method for sequestering atmospheric CO2 more effectively using mine waste rich in MgO.