Strong Interaction Research Articles

Molecular Weaving Towards Flexible Covalent Organic Framework Membranes for Efficient Gas Separations

AbstractCovalent organic frameworks (COFs) exhibit considerable potential in gas separations owing to their remarkable stability and tunable pore structures. Nevertheless, their application as gas separation membranes is hindered by limited size‐sieving capabilities and poor processability. In this study, we propose a novel molecular weaving strategy that combines hydroxyl polymers and 2D TpPa−SO3H COF nanosheets, achieving high gas separation efficiency. Driven by the strong electrostatic interactions, the hydroxyl chains thread through the COF pores, effectively weaving and assembling the composites to achieve exceptional flexibility and high mechanical strength. The penetrated chains also reduce the effective pore size of COFs, and combined with the “secondary confinement effect” stemming from abundant CO2 sorption sites in the channels, the PVA@TpPa−SO3H membrane demonstrates a remarkable H2 permeance of 1267.3 GPU and an H2/CO2 selectivity of 43, surpassing the 2008 Robson upper bound limit. This facile strategy holds promise for the manufacture of large‐area COF‐based membranes for small‐sized gas separations.

A fully coupled multiscale phase-change model at the porous interface for transpiration cooling: coupling dynamics pore-scale networks to continuum-scale free flow

Being a promising method for thermal protection system, transpiration cooling has received wide interest recently. Numerical simulation for transpiration cooling, however, has been limited due to the mis-matching between the pore-scale two-phase flow and external high-temperature aerothermodynamic environment, which induced by conventional decoupled or iterative one-way coupled simplification methods. In this work, a fully coupled continuum-scale and pore-scale model is established for transient transpiration cooling at the interface between boundary layer flow and porous medium through coupling Computational Fluid Dynamics (CFD) and Pore-Network Model (PNM), termed as the multiscale CFD-PNM coupled method. The coupled method allows to capture detailed displacement and phase change of two-phase flow at pore-scale, revealing the strong interaction of the water vapor with the external free flow within a high temperature boundary layer. After successfully validating the new coupled model by comparing with the Two-Phase Mixture Model (TPMM) solution, a number of cases mimicking the cooling at the interface of typical blunt bodies are simulated. The results show that the multiscale CFD-PNM coupled method can not only provide the thermal protection effect prediction, but also reveal many critical features that beyond the reach of continuum-scale studies. Some pore-scale phenomena that are important to the overall transpiration cooling effects are revealed, including transient phase change and composition variation of water vapor, imbibition and drainage of two-phase flow related to pore-scale capillary thresholds and applied boundary pressures, as well as the two-way mass transfer at the interface, such as the invasion of external hot air.

Effect of charge state on alkaline OER activity in FeN4–Gr catalyst supported on Ni (111) substrate

Abstract The catalysts of transition metal single−atom embedded in N−doped graphene (TMN4−Gr) have attracted significant attention due to the high utilization of transition metal atoms, remarkable selectivity and tunable catalytic activity. In this study, we have employed first−principles study to investigate alkaline OER activity of FeN4−Gr system supported on a Ni (111) substrate (FeN4−Gr/Ni). The results show that the Ni substrate can significantly enhance the OER activity of FeN4−Gr catalyst. The overpotential of FeN4−Gr/Ni catalyst is 0.63 V, much lower than 0.79 V of the FeN4−Gr, which is closely related to the strong interaction from the Ni substrate. By subtracting electrons from the FeN4−Gr/Ni catalyst, a positive charge environment can be created. It is found that, between the FeN4−Gr and the Ni substrate, a significant electron transfer phenomenon is observed, and the amount can be regulated by the charge state. Besides, the charge state can obviously tune the adsorption strength of *OOH intermediate through the interaction of Ni substrate, further optimizing the OER activity thermodynamically favorable. As the charge state increases to +1.55, the overpotential decreases to 0.23 V. By analyzing the integrated crystal orbital Hamilton populations, the chemical bond strength of Fe−O is discussed. Our results reveal that the Ni substrate can significantly enhance the OER activity of the FeN4−Gr catalyst, and the charge state can also tune the overpotential, offering valuable insights for the design of high−efficiency single−atom catalysts utilizing metal substrate.

One-pot fabrication of sodium deoxycholate based supramolecular self-healing antibacterial double network hydrogels

Double network (DN) hydrogels have emerged as a significant technology for enhancement of mechanical strength of weak supramolecular gels. In the present study, we report the one-pot route for design of a low molecular weight gelator based DN hydrogel wherein sodium deoxycholate (NaDC) forms the primary network entangled with agar matrix. Various compositions of the reported agar-NaDC hydrogels were examined through FTIR, sol-gel transition temperature (Tsg), XRD, circular dichroism (CD), scanning electron microscopy (SEM), hydrophobicity probe studies, Zeta potential studies and rheology measurements. Analysis of all studies together reveal that 1 mg/ml agar-NaDC DN hydrogel is the optimum composition that exhibits dense networking with primarily β-sheet like structure, highest mechanical strength as well as self-healing characteristics with reversed optical activity and highest Tsg. Antibacterial activity studied using inhibition zone method suggests that 1 mg/ml agar-NaDC gel demonstrates significant bactericidal effect unlike the pure gel with an inhibition zone of ∼25 mm against E.coli after 24 h and ∼32 mm after 48 h incubation. The antibacterial activity was unique for this composition of the DN hydrogel which is attributed to its reversal in optical activity exhibiting positive cotton effect resulting in stronger interaction with the bacterial cell wall. Additionally, nearly 2 times reduced water absorption capacity of the 1 mg/ml agar-NaDC DN hydrogel compared to pure NaDC hydrogel ensures the retention of its mechanical strength as well as other properties in high moisture containing environment. Hence, the 1 mg/ml agar-NaDC DN hydrogel holds appreciable potential as a novel strong supramolecular self-healing antibacterial hydrogel with sustained release characteristics primarily important for biomedical applications.

Dynamics of spin oscillation in double barrier synthetic antiferromagnet based magnetic tunnel junction in presence of spin-transfer torque

In this work, we have studied the spin dynamics of a synthetic antiferromagnet (AFM)/heavy metal/ferromagnet double barrier magnetic tunnel junction in the presence of Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction, interfacial Dzyaloshinskii–Moriya (iDM) interaction, Néel field, and Spin–Orbit Coupling (SOC) with different Spin-Transfer Torque (STT). We employ the Landau–Lifshitz–Gilbert–Slonczewski equation to investigate the AFM dynamics of the proposed system. We found that the system exhibits a transition from regular to damped oscillations with the increase in strength of STT for systems with a weaker strength of iDM interaction than RKKY interaction while displaying sustained oscillations for systems having the same order of RKKY and iDM interactions. On the other hand, the systems with sufficiently strong iDM interaction strength exhibit self-similar but aperiodic patterns in the absence of the Néel field. In the presence of the Néel field, the RKKY interaction dominating systems exhibit chaotic oscillations for low STT but display sustained oscillations under moderate STT. Our results suggest that the decay time of oscillations can be controlled via SOC. The system can work as an oscillator for low SOC but displays non-linear characteristics with the rise in SOC for systems having weaker iDM interaction than RKKY interactions. In contrast, opposite characteristics are noticed for iDM interaction dominating systems. We found periodic oscillations under low external magnetic fields in RKKY interaction dominating systems. However, moderate fields are necessary for sustained oscillation in iDM interaction dominating systems. Moreover, the system exhibits saddle-node bifurcations and chaos under moderate Néel field and SOC with suitable RKKY and iDM interactions. In addition, our results indicate that the magnon lifetime can be enhanced by increasing the strength of iDM interaction for both optical and acoustic modes.

Effect of supramolecular peptide hydrogel scaffold charge on HepG2 viability and spheroid formation.

Supramolecular bioinspired self-assembling peptide hydrogel (SAPH) scaffolds represent a class of fully defined synthetic materials whose chemical and mechanical properties can be finely engineered. In this study, the relationship between SAPHs physicochemical properties and HepG2 cells viability, spheroid formation and function are discussed. We first report that negatively charged SAPHs promote hepatocyte proliferation and spheroids formation in vitro 3D culture while positively charged SAPHs lead to hepatocyte death irrespective of the hydrogel mechanical properties. More specifically HepG2 cultured in 3D in E(FKFE)2 negatively charged SAPH maintained a differentiated phenotype and assembled into well-defined spheroids with strong cell-cell interactions. Furthermore, HepG2 spheroids responded to acetaminophen exposure with upregulation of key CYP450 enzymes expression clearly showing their potential for drug toxicity testing. These findings demonstrate how fine-tuned functional SAPH scaffolds can be used to identify key scaffolds parameters affecting cells. In this case we demonstrated the potential of negatively charged SAPHs for the 3D culture of HepG2 with potential applications in drug screening.

Enhancing the Encapsulation Performances of Liposomes for Amphiphilic Copolymers by Computer Simulations.

Liposomes, which encapsulate drugs into an inner aqueous core and demonstrate high drug-loading capacity, have attracted considerable interest in the field of drug delivery. Herein, the encapsulation processes for amphiphilic copolymers within liposomes have been investigated systematically to enhance the encapsulation capacity and optimize the structures using dissipative particle dynamics simulations. The results indicate that the physicochemical properties of lipids, receptors, and amphiphilic copolymers collectively determine the encapsulation behaviors of liposomes. Adjusting the hydrophobic interaction between hydrophobic tails of lipids (receptors) and hydrophobic blocks of copolymers, along with modulating the specific interaction between ligands and the functional head groups of receptors, can lead to various encapsulation capacities. Significantly, a medium hydrophobic interaction strength or a strong specific interaction is conducive to achieving a higher degree of encapsulation for amphiphilic copolymers. Furthermore, varying the key parameters, such as the hydrophobic interaction, the specific interaction, as well as the concentrations of lipids and receptors, can induce seven typical aggregate structures: heterogeneous, fully encapsulated, partially encapsulated, saturated-encapsulated, unsaturated-encapsulated, multilamellar, and column-like structures. The final phase diagrams are also constructed to provide a guideline for designing various structures of liposomes encapsulated with amphiphilic copolymers. These results significantly contribute to the illumination of strategies for the rational construction of the self-assembly system that facilitates the efficient encapsulation of amphiphilic copolymers within the inner aqueous core of liposomes, thereby providing valuable insights into the optimal design of liposome carriers for future biomedical applications.

Direct Three-Dimensional Observation of the Plasmonic Near-Fields of a Nanoparticle with Circular Dichroism.

Characterizing the spatial distribution of the electromagnetic fields of a plasmonic nanoparticle is crucial for exploiting its strong light-matter interaction for optoelectronic and catalytic applications. However, observing the near-fields in three dimensions with a high spatial resolution is still challenging. To realize efficient three-dimensional (3D) nanoscale mapping of the plasmonic fields of nanoparticles with complex shapes, this work established autoencoder-embedded electron energy loss spectroscopy (EELS) tomography. A 432-symmetric chiral gold nanoparticle, a nanoparticle with a high optical dissymmetry factor, was analyzed to relate its geometrical features to its exotic optical properties. Our deep-learning-based feature extraction method discriminated plasmons with different energies in the EEL spectra of the nanoparticle in which signals from multiple plasmons were intermixed; this component was key for acceptable 3D visualization of each plasmonic field separately using EELS tomography. With this methodology, the electric field of the plasmon that induces far-field circular dichroism was observed in 3D. The field linked to this chiroptical property was strong along the swirling edges of the particle, as predicted by a numerical calculation. This study provides insight into the correlation between structural and optical chiralities through direct 3D observation of the plasmonic fields. Furthermore, the strategy of implementing an autoencoder for EELS tomography can be generalized to achieve competent 3D analysis of other features, including the optical properties of the dielectrics and chemical states.

Photodetector Based on Elemental Ferroelectric Black Phosphorus-like Bismuth.

Two-dimensional ferroelectric materials have emerged as a promising candidate for the development of next-generation photodetectors owing to their inherent photogalvanic effect (PGE) and strong light-matter interactions. Recently, the first-ever elemental-based ferroelectric material, black-phosphorus-like Bi (BP-Bi), has been successfully synthesized. In this work, we investigate the PGE of the monolayer (ML) BP-Bi by using ab initio quantum transport simulation. We find that the photocurrent of the ML BP-Bi in the ferroelectric direction (armchair) is significantly larger than that in the vertical ferroelectric direction [zigzag (ZZ)]. For example, despite the comparable optical absorption rates of BP-Bi in the armchair (ARM) and ZZ directions, the maximum photocurrent (133 mA/W) in the ARM direction is 2 orders of magnitude greater than that (4.70 mA/W) in the ZZ direction. The asymmetry is attributed to the breaking and existence of the mirror inversion symmetries along the ARM and ZZ directions, respectively. Our work paves the way for the research of the low-dimensional ferroelectric photodetector.

Imaging shapes of atomic nuclei in high-energy nuclear collisions

Atomic nuclei are self-organized, many-body quantum systems bound by strong nuclear forces within femtometre-scale space. These complex systems manifest a variety of shapes1–3, traditionally explored using non-invasive spectroscopic techniques at low energies4,5. However, at these energies, their instantaneous shapes are obscured by long-timescale quantum fluctuations, making direct observation challenging. Here we introduce the collective-flow-assisted nuclear shape-imaging method, which images the nuclear global shape by colliding them at ultrarelativistic speeds and analysing the collective response of outgoing debris. This technique captures a collision-specific snapshot of the spatial matter distribution within the nuclei, which, through the hydrodynamic expansion, imprints patterns on the particle momentum distribution observed in detectors6,7. We benchmark this method in collisions of ground-state uranium-238 nuclei, known for their elongated, axial-symmetric shape. Our findings show a large deformation with a slight deviation from axial symmetry in the nuclear ground state, aligning broadly with previous low-energy experiments. This approach offers a new method for imaging nuclear shapes, enhances our understanding of the initial conditions in high-energy collisions and addresses the important issue of nuclear structure evolution across energy scales.

Pathogenic Mechanisms of Collagen TypeⅦA1 (COL7A1) and Transporter Protein Transport and Golgi Organization 1 (TANGO1) in Rheumatoid Arthritis: A New Therapeutic Target

Rheumatoid arthritis (RA) is an autoimmune disorder causing chronic inflammation primarily due to collagen regulation and transport imbalances. Collagen VII A1(COL7A1), a major component of anchoring fibrils, regulates inflammation via interacting with its transporter protein Transport and Golgi organization 2 homologs (TANGO1). The study revealed a significant increase in COL7A1 levels in both the plasma and PBMCs of RA patients. Additionally, a positive correlation between COL7A1 and ACCPA (anti-cyclic citrullinated peptide antibody) levels was observed among RA patients. TANGO1 mRNA expression was also found to be elevated in PBMCs. The knockdown of COL7A1 in RA synoviocytes using siRNA affected the expression of TANGO1 and inflammatory genes. Western blot analysis showed that COL7A1 si-RNA in TNF-α-induced SW982 cells reduced the expression of COL7A1, TANGO1, and NF-kBp65. The mRNA expression of inflammatory genes TNF-α, NF-kB p65, and IL-6 simultaneously decreased after the knockdown of COL7A1, as measured by qRT-PCR. An in silico analysis found 20 common interacting proteins of COL7A1 and TANGO1, with pathway enrichment analysis linking them to antigen presentation, class I and II MHC, and adaptive immunity pathways in RA. Among the common proteins, The DisGeNET database depicted that COL1A1, MIA3, SERPINH1, and GORASP1 are directly linked to RA. The molecular docking analysis of COL7A1 and TANGO1 revealed strong interaction with a −1013.4 energy-weighted score. Common RA-used drugs such as Adalimumab, Golimumab, and Infliximab were found to inhibit the interaction between COL7A1 and TANGO1, which can further impede the transport of COL7A1 from ER exit sites, indicating COL7A1 and TANGO1 as potential therapeutic targets to diminish RA progression.

Achieving Sub-ppm Sensitivity in SO2 Detection with a Chemically Stable Covalent Organic Framework.

We report the inaugural experimental investigation of covalent organic frameworks (COFs) to address the formidable challenge of SO2 detection. Specifically, an imine-functionalized COF (SonoCOF-9) demonstrated a modest and reversible SO2 sorption of 3.5 mmol g-1 at 1 bar and 298 K. At 0.1 bar (and 298 K), the total SO2 uptake reached 0.91 mmol g-1 with excellent reversibility for at least 50 adsorption-desorption cycles. An isosteric enthalpy of adsorption (ΔHads) for SO2 equaled -42.3 kJ mol-1, indicating a relatively strong interaction of SO2 molecules with the COF material. Also, molecular dynamics simulations and Møller-Plesset perturbation theory calculations showed the interaction of SO2 with π density of the rings and lone pairs of the N atoms of SonoCOF-9. The combination of experimental data and theoretical calculations corroborated the potential use of this COF for the selective detection and sensing of SO2 at the sub-ppm level (0.0064 ppm of SO2).

Achieving Sub‐ppm Sensitivity in SO2 Detection with a Chemically Stable Covalent Organic Framework

AbstractWe report the inaugural experimental investigation of covalent organic frameworks (COFs) to address the formidable challenge of SO2 detection. Specifically, an imine‐functionalized COF (SonoCOF‐9) demonstrated a modest and reversible SO2 sorption of 3.5 mmol g−1 at 1 bar and 298 K. At 0.1 bar (and 298 K), the total SO2 uptake reached 0.91 mmol g−1 with excellent reversibility for at least 50 adsorption‐desorption cycles. An isosteric enthalpy of adsorption (ΔHads) for SO2 equaled −42.3 kJ mol−1, indicating a relatively strong interaction of SO2 molecules with the COF material. Also, molecular dynamics simulations and Møller–Plesset perturbation theory calculations showed the interaction of SO2 with π density of the rings and lone pairs of the N atoms of SonoCOF‐9. The combination of experimental data and theoretical calculations corroborated the potential use of this COF for the selective detection and sensing of SO2 at the sub‐ppm level (0.0064 ppm of SO2).

Fe-Doped Ni3S2 Induces Self-Reconstruction for Urea-Assisted Water Electrolysis Enhancement.

Urea oxidation reaction (UOR) is an attractive alternative anodic reaction to oxygen evolution reaction (OER) for its low thermodynamic potential (0.37 V vs RHE). A major challenge that prohibits its practical application is the six-electron transfer process during UOR, demanding enhancements in the catalytic activity. Herein, a Fe-doped Ni3S2 catalyst with a uniform flower-like structure is synthesized in situ on nickel foam via a simple one-step hydrothermal method. The electrochemical properties of Fe-Ni3S2 are significantly improved since a current density of 10 mA cm-2 only requires a 1.33 V potential and remains stable for 60 h. The structural characterization demonstrates a strong interaction between Fe and Ni3S2. After Fe doping, the active site increases, which promotes the formation of NiOOH on the catalyst surface, thus speeding up the UOR process. These changes are beneficial to charge transfer and optimize the adsorption energy of the intermediates. In situ EIS further confirms that Fe promotes electron transfer during the UOR process, reduces the interface resistance between the catalyst and the electrolyte, and lowers the driving voltage.

Design, characterization, and bioactivity evaluation of novel symmetrical N,N'-benzene-1,2-diylbis[1-(2-chloroquinolin-3-yl)methanimine] based metal complexes

This study presents the synthesis and characterization of two novel metal complexes derived from the symmetrical Schiff base N,N'-benzene-1,2-diylbis[1-(2-chloroquinolin-3-yl)methanimine] (OBCQ), coordinated with Nickel(II) (NiOBCQ) and Copper(II) (CuOBCQ). The structural elucidation of these complexes was achieved through a comprehensive suite of analytical techniques, including elemental analysis, UV–visible spectroscopy, mass spectrometry, infrared spectroscopy, magnetic susceptibility, conductivity measurements, and thermal analysis. The data confirm that both NiOBCQ and CuOBCQ adopt octahedral geometries, formulated as [Ni(OBCQ)(H₂O)₂(Cl)₂] and [Cu(OBCQ)(H₂O)₂(Cl)₂], respectively. Density Functional Theory (DFT) calculations were employed to validate the molecular structures and explore the quantum chemical parameters of OBCQ and its metal complexes. Additionally, in vitro assessments of anti-inflammatory and antioxidant activities revealed enhanced bioactivity for the metal complexes compared to the free OBCQ ligand. Molecular docking studies against key proteins (5IKT for Human Cyclooxygenase-2 and 5IJT for Human Peroxiredoxin 2) highlighted strong binding affinities and molecular interactions, suggesting that OBCQ and its metal complexes hold significant promise as novel therapeutic agents with multifaceted biological activities.

Three-dimensional Covalent Organic Framework with Dense Lithiophilic Sites as Protective Layer to Enable High-Performance Lithium Metal Battery.

Lithium (Li) metal batteries with remarkable energy densities are restrained by short lifetime and low Coulombic efficiency (CE), resulting from the accumulative Li dendrites and dead Li during cycling. Here, we prepared a new three-dimensional (3D) covalent organic framework (COF) with dense lithiophilic sites (heteoatom weight contents of 32.32wt%) as an anodic protective layer of Li metal batteries. The 3D COF was synthesized using a [6+4] synthesis strategy by inducing flexible 6-connected cyclotriphosphazene derivative aldehyde and 4-connected porphyrin-based tetraphenylamines. Both phosphazene and porphyrin rings in the COF served as electron-rich and lithiophilic sites, enhancing a homogeneous Li+ flux via 3D direction towards highly smooth and compact Li deposition. The Li/Por-PN-COF-Cu cells achieved a record average CE of 99.1% for 320 cycles with smooth Li deposition. Meanwhile, the abundant lithiophilic sites can promote fast Li+ transport with Li+ transference number of 0.87, enabling LiFePO4 full cell with stable stripping/plating processes even at a harsh rate of 5 C. Theoretical calculations revealed that the strong interaction force between Li+ and the COF facilitated the dissolution of Li+ from the electrolyte, and the low migration barrier of 1.08 eV indicated a favorable interaction between the Li+ ions and the π-electron system.

Three‐dimensional Covalent Organic Framework with Dense Lithiophilic Sites as Protective Layer to Enable High‐Performance Lithium Metal Battery

Lithium (Li) metal batteries with remarkable energy densities are restrained by short lifetime and low Coulombic efficiency (CE), resulting from the accumulative Li dendrites and dead Li during cycling. Here, we prepared a new three‐dimensional (3D) covalent organic framework (COF) with dense lithiophilic sites (heteoatom weight contents of 32.32wt%) as an anodic protective layer of Li metal batteries. The 3D COF was synthesized using a [6+4] synthesis strategy by inducing flexible 6‐connected cyclotriphosphazene derivative aldehyde and 4‐connected porphyrin‐based tetraphenylamines. Both phosphazene and porphyrin rings in the COF served as electron‐rich and lithiophilic sites, enhancing a homogeneous Li+ flux via 3D direction towards highly smooth and compact Li deposition. The Li/Por‐PN‐COF‐Cu cells achieved a record average CE of 99.1% for 320 cycles with smooth Li deposition. Meanwhile, the abundant lithiophilic sites can promote fast Li+ transport with Li+ transference number of 0.87, enabling LiFePO4 full cell with stable stripping/plating processes even at a harsh rate of 5 C. Theoretical calculations revealed that the strong interaction force between Li+ and the COF facilitated the dissolution of Li+ from the electrolyte, and the low migration barrier of 1.08 eV indicated a favorable interaction between the Li+ ions and the π‐electron system.

Self-assembled ILs-PVA micelle nanostructure impart the pervaporation membrane with high ethanol dehydration performance

Achieving strong interaction with the targeted composition and constructing abundant transport channels is crucial to obtain the pervaporation (PV) membrane with high selectivity and flux. Here, three ionic liquids (ILs) were screened out based on their relative selectivity and capacity targeting for bioethanol dehydration by COSMO-RS. The interaction energies analysis between ILs, EtOH, and H2O suggests that the ILs can form strong hydrogen bonds with water and disrupt the hydrogen bond in the EtOH–H2O azeotropic mixture, which is beneficial for improving the selectivity. Furthermore, driven by the multiple hydrogen bonds, electrostatic interactions, and van der Waals forces, ILs could self-assemble with polyvinyl alcohol (PVA) to fabricate the PV membrane with well-ordered micelle nanostructure, as its structure was revealed by MD simulations. The formation of the ILs-PVA micelle dramatically influenced membrane surface morphology, roughness, and water contact angle, providing an extra transport channel for the membrane. The optimal membrane (at the cmc point) exhibited a superior ethanol dehydration separation factor of 1627, along with a flux of 684 g/m2h at 50 °C. It can be expected that this novel self-assembled ILs-PVA micelle nanostructure strategy will find promising applications in other azeotropic mixture separation processes, like ethanol-ethyl acetate, water-butanol, etc.

Ultra-Low Threshold Resonance Switching by Terahertz Field Enhancement-Induced Nanobridge.

Ongoing efforts spanning decades aim to enhance the efficiency of optical devices, highlighting the need for a pioneering approach in the development of next-generation components over a broad range of electromagnetic wave spectra. The nonlinear transport of photoexcited carriers in semiconductors at low photon energies is crucial to advancements in semiconductor technology, communication, sensing, and various other fields. In this study, ultra-low threshold resonance mode switching by strong nonlinear carrier transport beyond the semi-classical Boltzmann transport regime using terahertz (THz) electromagnetic waves are demonstrated, whose energy is thousands of times smaller than the bandgap. This is achieved by employing elaborately fabricated 3D tip structures at the nanoscale, and nonlinear effects are directly observed with the THz resonance mode switching. The nanotip structure intensively localizes the THz field and amplifies it by more than ten thousand times, leading to the first observation of carrier multiplication phenomena in these low-intensity THz fields. This experimental findings, confirmed by concrete calculations, shed light on the newly discovered nonlinear behavior of THz fields and their strong interactions with nanoscale structures, with potential implications and insights for advanced THz technologies beyond the quantum regime.

Exploring Chlorinated Solvents as Electrolytes for Lithium Metal Batteries: A DFT and MD Study

ABSTRACTElectrolytes with fluorinated solvents have been regarded as a promising strategy to stabilize high‐voltage cathodes and the interphase of lithium anode in lithium metal batteries (LMBs). However, the rigorous synthesis approach and high cost have led to a demand for developing cost‐effective solvents with suitable properties for LMBs. Herein, we explored the possibility of using chlorinate solvents as electrolytes using density functional theory (DFT) and classical molecular dynamics (MD) simulation. Taking ether (1,2‐dimethoxyethane [DME], 1,3‐dioxolane [DOL]), carbonate (dimethyl carbonate [DMC], and ethylene carbonate [EC]) as examples, we first compared the energy variation of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) upon Cl and F substitution. In particular, we found that 1,2‐bis(chloromethoxy)ethane (DME‐2Cl‐2) has the lowest HOMO and the highest LUMO level among the chlorinated DME after coordinating with Li+, enabling a potentially wide voltage stability. Further MD simulation reveals that lithium ions in DME‐2Cl‐2 has a weaker solvation coordination with solvents but stronger interaction with anions than DME and 1,2‐bis(Fluoromethoxy)ethane (DME‐2F‐2), which is more beneficial for forming stable anion‐derived solid electrolyte interphase (SEI). Our findings suggest that chlorinated solvents can be used as promising electrolytes for LMBs.