Browse Articles

Cr‐Leaching Induced Vacancy Engineering for High‐Performance Anion Exchange Membrane Water Electrolysis

ABSTRACT Anion exchange membrane water electrolysis (AEMWE) offers a compelling route to large‐scale green hydrogen production. However, developing catalysts that simultaneously combine high activity, long‐term durability, and stack‐level scalability remains a major challenge. Here, we report a magnetron‐sputtered NiFeCr 2 thin‐film catalyst that delivers 3 A cm − 2 at 1.77 V and 8.54 A cm − 2 at 2.10 V in an AEMWE membrane electrode assembly at 60°C, while maintaining stable operation at 2 A cm − 2 for 1798 h. Notably, the thin‐film catalyst was further assembled into a 15 × 100 cm 2 electrolyzer stack, delivering a peak power of 12.87 kW and validating its practical scalability. In situ spectroscopic characterization and electrochemical mechanistic studies reveal that electrochemical reconstruction induces partial Cr dissolution and the concomitant formation of active Ni/FeOOH phases, while confirming that NiFeCr 2 operates via a lattice‐oxygen‐mediated mechanism. Density functional theory calculations indicate Cr vacancies increase metal–oxygen covalency, strengthen adsorption of oxygenated intermediates, and lower free energy barriers for oxygen evolution reaction.

Heterocyclic Nanographenes Doped with Boron and Phosphorus: Post‐Phosphorization Synthesis, Excited‐State Dynamics and Ion‐Responsive Properties

ABSTRACT Incorporating more than one kind of heteroatom into polycyclic aromatic hydrocarbons is a powerful method for achieving diversiform heterocyclic structures and desirable physical properties. Herein, we disclose precise post‐phosphorization of conjugated organoboranes, which enables the successful synthesis of unprecedented boron‐/phosphorus‐codoped nanographenes. Two as‐obtained heterocyclic molecules, featuring boron atoms and phosphine oxide groups at the zigzag edges, show the curved C 42 B 2 P and C 42 B 2 P 2 frameworks, respectively, attributed to the structural distortion effects of the phosphorus‐containing hexagonal rings. They display intriguing properties, such as disturbed aromaticity, enhanced electron affinity, and enlarged energy gaps. Notably, the blue‐shifted stimulated emission and amplified spontaneous emission characteristics are observed, demonstrating not only the important effects of the boron atoms and phosphorus units but also their potential optical‐gain and lasing utility. Furthermore, the sulfuration reaction of the phosphorus center produced another heterocyclic derivative containing the phosphine sulfide units. Coordination of its boron atoms and phosphine sulfide groups with the fluoride and silver ions, respectively, is realized, indicating its uncommon dual ion‐responsive properties. This post‐phosphorization strategy, along with these findings, will inspire research of boron/phosphorus‐containing heterocycle chemistry and materials.

Polymer Composites of Ultra‐Small Nanoparticles: Coupled Dynamics for Synergistic Processability

ABSTRACT Ultra‐small nanoparticles (USNPs), characterized by fast dynamics, ultra‐small dimensions and dense surface functionalities, offer an underexplored yet powerful strategy to simultaneously modulate polymer behavior and NP assembly. Herein, we introduce a versatile materials design strategy based on USNP complexation to reprogram polymer chain dynamics and manipulate NP ordering. Using 1 nm metal oxide NP, H 3 PW 12 O 40 (PTA) complexed with polyvinyl alcohol (PVA), we show that USNPs induce anomalous viscosity reduction via chain collapse, enabling residual‐stress‐free film fabrication. The size of PTA, significantly smaller than the polymer coil dimensions, combined with strong attractive interactions to PVA chains, induces chain collapse in solution. Their ultrahigh surface area disrupts polymer crystallinity and forms humidity‐responsive supramolecular networks, demonstrating a humidity‑assisted proof‑of‑concept route for optical‑film orientation and fixation. Moreover, the energy barrier for USNP dynamics is substantially lower than that of colloidal NPs, allowing stretch‐induced orientation under uniaxial extension. In situ x‐ray scattering confirms unidirectional PTA orientation upon mechanical stretching, yielding promising birefringence (Δ n ≈ 0.018). This work establishes USNP complexation as a versatile strategy to simultaneously reprogram polymer processability and achieve precise NP ordering for functional devices.

Targeting m6A writer METTL3 with engineered nanovesicles reduces neuroinflammation in vitro and in vivo

Abstract Epigenetic editing, particularly N 6 -methyladenosine (m 6 A) modification, represents a promising therapeutic strategy by silencing genes without altering DNA sequence. However, in vivo epigenetic intervention of neuroinflammation remains challenging and has rarely been explored. Here we developed a hybrid epigenetic nanomodulator, siMETTL3-hNVs, by integrating natural microglia-derived nanovesicles (NVs) with synthetic liposomes pre-loading small interfering RNA targeting the m 6 A writer methyltransferase-like 3 (METTL3). Natural NVs enabled siMETTL3-hNVs to achieve inflamed-brain delivery through CCR2-CCL2 chemotaxis and caveolae-mediated transcytosis across the blood-brain barrier. More importantly, relying on abundant cytokine receptors on the NVs, siMETTL3-hNVs served as decoys to neutralize pro-inflammatory cytokines, synergizing with the intracellular silencing of METTL3 to drive microglial M2 repolarization. In female mouse models of acute neuroinflammation and radiation-induced brain injury, siMETTL3-hNVs treatment significantly reduced cytokine levels, attenuated hippocampal damage, and ameliorated cognitive deficits. This work overcomes critical delivery bottlenecks in m 6 A-based therapeutics and establishes a robust strategy for epigenetic reprogramming of neuroinflammation.

Discovery of a peripheral Myh11-expressing nucleus pulposus cell population demontrating therapeutic potential for disc degeneration

Thermoplastic modification of polycrystalline copper surface microstructure by nonmelting nanosecond laser pulses

Mechanisms of surface relief formation on bulk polycrystalline oxygen-free copper samples under single and multiple UV nanosecond laser pulses (355 nm, 10 ns) in air are investigated. The laser spot size ∼100 μm is several times larger than the average size ∼40 μm of crystal grains. Incident fluences are limited by ∼1 J/cm2 to avoid melting of copper. Confocal laser microscopy, scanning electron microscopy, and transmission electron microscopy are utilized to reveal the deformation processes leading to surface relief development. It is found that irradiation uncovers the grain boundaries on the exposed surface. Dislocation subboundaries and packets of nanoscale plates of deformation twins near the grain boundaries are observed in a subsurface layer of 20–100 nm thick. According to our theoretical analysis and simulations, the observed surface modification is caused by nonuniform plastic deformation of crystallites induced by nonmelting laser heating. Continuum modeling of such heating shows that the shockwave effects are negligible since the generated acoustic waves have a pressure of less than 100 atm. We demonstrate that the solid copper goes to the plastic deformation regime if the temperature rise exceeds ∼250 °C. Atomistic simulation of polycrystals reveals anisotropy of grain deformation and asynchronous plastic response due to their different stiffnesses depending on lattice orientation, as well as the residual stresses and growth of surface roughness after each heating–cooling cycle. The obtained results are important for understanding the physical mechanisms of surface degradation of copper mirrors under laser induced thermocycling.

Decoupling nonlinear programmability from resonance tuning in a spectrally stable graphene–GaN terahertz nanocavity

Electrically tunable graphene metasurfaces commonly rely on Fermi-level modulation to reshape plasmonic resonances, a process that inherently couples amplitude control to undesirable resonance-frequency shifts. This work introduces a mechanism to bypass this trade-off: field-programmed second-harmonic generation (SHG) within a spectrally stable graphene–GaN terahertz nanocavity. By applying a vertical DC field, we activate an effective second-order nonlinear response at the graphene–GaN interface through electric-field-induced second-harmonic generation. Crucially, the cavity-backed hybrid mode remains nearly invariant under bias, effectively decoupling the nonlinear source modulation from resonance-frequency tuning. Full-wave nonlinear simulations confirm electrically programmable SHG emission with minimal resonance pulling, stable near-field profiles, and multi-resonant SH spectra. This platform, leveraging multi-resonant enhancement from hybrid cavity-plasmon modes, provides a robust architecture for spectrally stable, active nonlinear terahertz metasurfaces.

Lanthanide ion electronic structure controls magnetic excitations in topological quantum ferrimagnets LnMn6Sn6 (Ln = Tb, Dy, Ho)

The LnMn6Sn6 family of topological magnets is a promising platform for next-generation spintronic and magnonic technologies. However, the influence of the lanthanide ion (Ln3+) on the excited-state spin dynamics, or magnons, remains a critical knowledge gap. Here, we present the first comparative study of the magnetic dynamics in LnMn6Sn6 materials (Ln = Tb, Dy, Ho) using Brillouin light scattering. Our findings reveal a direct correlation between the lanthanide ion’s intrinsic properties and the magnon behavior. We demonstrate that the magnon frequency in the absence of an applied magnetic field is primarily dictated by the strength of the lanthanide exchange coupling, as modeled by its relationship with the de Gennes factor. The response of the magnon to an applied field is influenced by material's gyromagnetic ratio and the overall anisotropy of the material, which are dictated by total angular momentum and the anisotropy of the lanthanide sublattice, respectively. These results establish that simple lanthanide substitution provides a powerful and predictable method for tuning magnon properties, enabling the rational design of materials for advanced technological applications.

Revealing nanoscale motion under photon limited coherent x-ray diffraction

Time-resolved coherent x-ray diffraction provides a powerful probe of nanoscale dynamics. Yet its extension beyond static imaging is constrained by photon exposure, background scattering, and instability of phase retrieval when individual diffraction frames are weak. Here, we demonstrate an in situ coherent x-ray diffraction approach that detects nanoscale motion even when frame-by-frame image reconstruction becomes unreliable. The method combines a microelectromechanical systems (MEMS) tensile platform, providing periodic mechanical actuation and time-resolved displacement readout, with coherent hard x-ray diffraction at a synchrotron nanoprobe. Using a self-assembled gold nanoparticle superlattice, we perform ptychography to obtain an experimentally calibrated complex probe and a high-resolution object. These serve as a reference for a probe-informed forward model that reproduces realistic diffraction movies under exposure-limited conditions, including photon-shot noise. We show that conventional frame-by-frame coherent diffraction imaging reconstructions are then dominated by reconstruction variability and scattering from nearby device features. To overcome these limitations, we use the measured MEMS displacement signal as an independent temporal reference and apply lock-in demodulation to the diffraction time series. This analysis isolates the periodic scattering response synchronized with the applied mechanical drive, while suppressing the large mean diffraction signal, slow drift, and broadband noise. As a result, nanoscale motion remains detectable as lock-in phase signatures even when individual diffraction frames cannot support stable retrieval of the whole lattice as an image. Our results establish this technique as a robust strategy for accessing periodic, drive-synchronized dynamics in exposure-limited coherent x-ray diffraction experiments, and guide future in situ studies of device-integrated nanomaterials.

Interfacial structural modification in Cu/low- <i>k</i> interconnects revealed by atomic force microscopy infrared spectroscopy

Process-induced modification confined to the immediate vicinity of Cu/low-k interfaces is a key issue in advanced interconnects, yet direct vibrational-band-specific characterization of this region on the tens-of-nanometers scale remains difficult. Here, resonance-enhanced atomic force microscopy (AFM) infrared spectroscopy has been applied from the upper surface of a practical damascene Cu/low-k interconnect structure comprising 330 nm wide Cu lines separated by 270 nm in a 200 nm thick, porous SiOC-based dielectric film, enabling direct comparison of the central low-k region and the interface-adjacent region. Local spectroscopy together with a 15-point line scan at an 18 nm step interval revealed reduced Si–CH3-related and Si–H-related vibrational responses and an enhanced OH-related response, including possible contributions from Si–OH, hydrogen-bonded hydroxyl species, and adsorbed water, near the Cu/low-k interface, with the most pronounced methyl-related change observed at the first low-k measurement point adjacent to the boundary. This direct nanoscale identification of interfacial structural modification has been enabled by resonance-enhanced photothermal detection and AFM-based positional control and has been demonstrated directly on a practical top-surface device structure without preparing a special cross-sectional specimen. The observed interfacial chemistry is consistent with localized demethylation, modification of Si–H-related environments, and increased hydroxyl/water-related character and is, therefore, consistent with the formation of a locally higher-k interfacial zone, which is expected to contribute to increased capacitance, leakage risk, and breakdown susceptibility in practical low-k interconnects.

Suppressing anisotropy in nanostructured Fe/Ni superlattices with monolayer periodicity

We described here the growth of carefully engineered Fe/Ni(100) superlattices with monolayer periodicity (i.e., Fe50Ni50) on a Cu(100) crystalline substrate, nanostructured to 70 × 40 nm islands. The nanometer-thick, islanded Fe/Ni(100) superlattices are characterized in terms of composition, crystalline structure, and magnetic properties and show a magnetic behavior perfectly isotropic in-plane, with negligible effective anisotropy out of plane because the strongly reduced shape anisotropy due to the single-domain islands almost exactly compensates the perpendicular interfacial anisotropy due to the Fe/Ni layering. The suppression of anisotropy is achieved without nanolithography processes or in situ application of larger magnetic fields. The nanostructured films show a small coercivity [although 20 times larger than the ones grown on flat Cu(100) substrates]. The reduced shape anisotropy in the nanostructured superlattice accounts for the observed suppression of the effective anisotropy in-plane and out-of-plane.

Enhancing optical confinement in hybrid surface plasmonic nanocavities via external mode coupling near avoided resonance crossings

Plasmonic devices have been intensively studied in the past few decades. However, the substantial intrinsic ohmic losses imposed by noble metals highly limited further applications of such devices. Herein, we demonstrate the formation of long-lived states via external mode coupling in coupled hybrid surface plasmonic nano-resonators in which improved Q factors have been achieved. By systematically engineering the spatial intervals between three silicon nanorods on a silver substrate, we demonstrate the formation of long-lived states through destructive interference of optical fields. Numerical simulations reveal that, at a critical spacing, the Q factor of a resonant mode is significantly boosted to approximately 450—an eightfold enhancement compared to isolated single-rod resonators. Notably, this drastic improvement in photon lifetime is achieved while maintaining an ultrasmall effective mode volume Veff of the order of 10−4 μm3. These findings provide an alternative strategy to material optimization for mitigating metallic losses, offering a robust framework for developing high-efficiency, low-threshold plasmonic nanolasers, and advanced on-chip photonic components.

Influence of implantation and annealing temperatures on electrical property of low-dose implanted/annealed SiC

Terahertz time-domain ellipsometry was used to examine the electrical properties of low-dose implanted/annealed silicon carbide (SiC) subjected to different implantation and annealing temperatures. P- and Al-implantations were performed at a dose of 2 × 1013 cm−2 and at implantation temperatures of 30 and 500 °C, and the samples were subsequently annealed at 1200 and 1600 °C. For both the P- and Al-implanted/annealed SiC, resistivity was halved when the implantation temperature was increased from 30 to 500 °C. The decrease in resistivity is attributed to the suppression of implantation-induced damage at 500 °C. The resistivity of the P-implanted/annealed SiC decreased drastically as the annealing temperature was increased from 1200 to 1600 °C owing to electrical activation. However, for the Al-implanted/annealed SiC, the resistivity showed little change with increasing annealing temperature. The high ionization energy of Al is considered to have inhibited the reduction in resistivity. These results demonstrate the importance of controlling the implantation and annealing temperatures, even for low-dose implantation.

Pronounced bias-enhanced photocurrent with strong polarization sensitivity in 1T-TiSe2-based photodetectors

We report a 1T-TiSe2-based photodetector with pronounced polarization sensitivity and broadband visible-light photoresponse under low-bias conditions. Using a combined density-functional theory and nonequilibrium Green’s function approach, we calculate the transmission spectra and photocurrent under linearly polarized illumination. The photocurrent exhibits strong dependences on both photon energy and polarization angle and can be enhanced by up to two orders of magnitude under applied bias, with a concomitant increase in the extinction ratio. Analysis of the transmission spectra identifies the specific electronic transitions responsible for the photocurrent maxima. These results demonstrate an effective electrical approach to enhancing the photoresponsivity of low-dimensional photodetectors.

Growth window and wurtzite phase stability of molecular-beam-epitaxial ScInN thin films with composition-dependent photoluminescence

We establish the growth window and wurtzite phase stability of plasma-assisted molecular-beam-epitaxial ScInN thin films over a broad composition range. Lower growth temperatures suppress rock salt phase formation and enable wurtzite ScInN without detectable rock salt contributions up to x(Sc) = 0.36. X-ray diffraction reveals systematic composition-dependent changes in phase formation and lattice parameters. We observe a pronounced anisotropic lattice evolution, with the in-plane lattice parameter a showing only a minor dependence on scandium content, whereas a decrease in the out-of-plane lattice parameter c is more pronounced. This trend is consistent with results from density functional theory calculations we performed using the SCAN functional, as well as Raman spectroscopy measurements showing a strong shift of the A1(LO) modes and a much smaller shift of the E2 mode. Photoluminescence is observed across the investigated alloy series, with the maximum emission shifting from 0.85 eV for InN to 2.07 eV for x(Sc) = 0.40. These results establish molecular-beam-epitaxial ScInN as an experimentally accessible alloy system with an extended wurtzite stability range, a composition-dependent optical response, and a nearly constant in-plane lattice parameter enabling heterostructure design with reduced lattice mismatch.

Oxygen concentration effect on the behavior of point defects in YBa2Cu3O6.5−7: A first-principles study

Understanding defect behavior in high-temperature superconducting magnet materials, such as yttrium barium copper oxide (YBa2Cu3O7−δ), is vital for predicting changes in their superconducting properties during operation in compact fusion reactors. First-principles density functional theory (DFT) calculations are used to investigate the energetics of point defects in oxygen-deficient YBa2Cu3Ox (6.5 ≤ x &amp;lt; 7) in comparison to YBa2Cu3O7. With decreasing oxygen stoichiometry, the formation energies of oxygen vacancies generally increase, while those of interstitials decrease. The formation energies of single cation defects as a function of oxygen stoichiometry are similar. Oxygen is predicted to diffuse along b-axes via a vacancy mechanism with an activation energy of around 0.5 eV. The diffusion activation energy of oxygen defects in oxygen-deficient YBa2Cu3Ox is larger than that in YBa2Cu3O7 without oxygen vacancies. The mean recombination energy of oxygen Frenkel pairs slightly increases with decreasing oxygen concentration. The formation energy of Frenkel pairs in oxygen-deficient YBa2Cu3Ox, particularly at x ≈ 6.9, is lower relative to YBa2Cu3O7, resulting in a higher number of irradiation defects in YBa2Cu3Ox; additionally, full-chain oxygen vacancy configurations in YBa2Cu3Ox (x = 6.75, 6.50) enhance material stability under irradiation relative to the x ≈ 6.9 structure.

Three-dimensional kinetic Monte Carlo modeling of disordered organic semiconductor devices with molecular doping

Molecular doping plays a pivotal role in enhancing the performance of organic light-emitting diodes, particularly by facilitating charge injection across large energy barriers at the electrode/organic interfaces. Recently, it has been shown that the Schottky-contact formation between metal electrodes and molecularly doped disordered organic semiconductors leads to modified charge-carrier mobilities compared to undoped bulk materials, smaller depletion widths than inorganic semiconductors, as well as ultraslow charge-carrier dynamics [Yu et al., Phys. Rev. Appl. 19, 024041 (2023)]. These results bring up the question whether conventional one-dimensional drift–diffusion approach can accurately model devices with doped injection layers. In this work, to gain a comprehensive understanding of the microscopic mechanisms involved, we systematically investigate disordered organic semiconductor devices with molecular doping using three-dimensional kinetic Monte Carlo simulations and compare with a one-dimensional drift–diffusion model. We find that for full-device simulations, (a) one-dimensional drift–diffusion approach overestimates current density (without special treatment of mobility in the doped layer); (b) one-dimensional drift–diffusion approach overestimates the depletion layer width; and (c) although the dynamics of carrier profiles could be slow (∼10−5 s), the device current density can reach a steady state much faster (∼10−6 s). The three-dimensional kinetic Monte Carlo simulations are employed to study both single doped layers and bipolar doped layers (P–N junctions) and are shown to well reproduce experimental current density–voltage characteristics.

Revealing the effects of particle shape and distribution on the direct wafer-to-wafer bonding dynamics

Particle contamination control is one of the most critical challenges in wafer-to-wafer (W2W) hybrid bonding technology. Particles induce voids at the bonding interface, thereby compromising the bonding quality and reliability. However, the effects of particle shape and distribution on the W2W pre-bonding process have not yet been investigated. In this work, three-dimensional (3D) W2W hybrid bonding analysis involving particles was conducted. The influence of particle on bonding front propagation was analyzed. Besides, the effects of particle shape and position on bonding time, interfacial void size, and upper wafer von Mises stress were quantitatively evaluated. The results show that the presence of particle leads to the split of the bonding front and a pronounced delay in bonding time. Compared with the cylindrical particle, the square particle results in a longer bonding delay (4.4 s vs 3.1 s) and produces a larger void height (17.1 μm vs 11.1 μm). Moreover, it is found that particle contamination significantly amplifies the void defects. Particle position is found to have a non-monotonic influence on bonding dynamics. As the particle location gradually moves away from the wafer center, the area and height of void, as well as the total bonding time exhibit a trend of first increasing and then decreasing. Specifically, a cylindrical particle located at 70–80 mm from wafer center generates the largest void area (up to 2350 mm2), the highest void height (14.8 μm), and the longest bonding time (3.6 s). This study offers a quantitative guidance for contamination control in 3D heterogeneous integration technology.

Effect of ions on the ultrafast dynamics of electron–phonon and phonon–phonon interactions in gold nanospheres in water

Modulating localized surface plasmon resonances (LSPRs) plays an essential role in the incorporation of metal nanoparticles (MNPs) in various applications. For instance, the ability to tune the LSPR frequency by varying the size and shape of MNPs is crucial for photodetection and imaging applications. This work reports on the effect of tuning the ionic strength around gold (Au) NPs on the dynamics of electron–phonon and phonon–phonon interactions. Steady-state and transient absorption spectroscopies are employed to investigate the effect of NaCl salt on LSPRs in Au-NPs in water. The results indicated that the presence of the Na+ and Cl− ions leads to a ∼3 nm-“red” shift of the plasmon resonance, and the formation of weak broad absorption bands on the wings of the LSPR peak. Pump–probe experiments show that, after excitation of Au-NPs at ∼400 nm, the lifetimes of electron–phonon and phonon–phonon interactions increase linearly with NaCl molarity, which is similar to their dependence on excitation power and, thus, on the density of photogenerated charge carriers. These effects are attributed to the change of the dielectric environment induced by the presence of Na+ and Cl− ions on the surface of Au-NPs, which alters the plasmon damping rates, and the change in the lifetimes of electron–phonon and phonon–phonon interactions is assigned to modifications of the surface electron density. Adjusting LSPR dynamics by tuning the ionic strength of the surroundings opens new horizons for the application of plasmonic devices with enhanced functionality.

On the amorphous to crystalline structure transition of oxidized LEAs

Oxide crystallization in multicomponent alloys is often delayed relative to mono-metals, yet the mechanisms underlying this behavior remain incompletely understood. Here, we investigate the relationship between oxygen saturation and crystallization in thin-film mono-metals and low-entropy alloys (LEAs) by introducing two temperatures in our annealing experiment: the thickness saturation temperature (Tf), marking completion of oxygen uptake, and the oxide crystallization temperature (T2), marking the onset of crystalline oxide formation. We show that mono-metals typically crystallize prior to or concurrent with saturation (T2 ≤ Tf), whereas LEAs generally show the opposite (T2 &amp;gt; Tf), indicative of delayed oxide crystallization. Therefore, we define the difference (T2 − Tf) as the crystallization delay strength (CDS), providing a quantitative metric for comparing oxide crystallization behavior across compositions. By correlating key oxide uptake saturation and crystallization temperatures (Tf, T2, thus also CDS) with bond-character descriptors derived from the Van Arkel–Ketelaar model, we show that bond ionicity and covalency systematically influence oxygen saturation and crystallization delay. We report that LEAs with higher ionicity show lower saturation temperatures Tf and increased crystallization delay, while more covalent alloys crystallize without significant CDS. These results establish bond character as a predictive descriptor for oxide crystallization behavior in alloy thin films.