High-Entropy Transition Metal Phosphorus Trichalcogenides for Rapid Sodium Ion Diffusion.

High-entropy strategies are regarded as a powerful means to enhance performance in energy storage fields. The improved properties are invariably ascribed to entropy stabilization or synergistic cocktail effect. Therefore, the manifested properties in such multicomponent materials are usually unpredictable. Elucidating the precise correlations between atomic structures and properties remains a challenge in high-entropy materials (HEMs). Herein, atomic-resolution scanning transmission electron microscopy annular dark field (STEM-ADF) imaging and four dimensions (4D)-STEM are combined to directly visualize atomic-scale structural and electric information in high-entropy FeMnNiVZnPS3. Aperiodic stacking is found in FeMnNiVZnPS3 accompanied by high-density strain soliton boundaries (SSBs). Theoretical calculation suggests that the formation of such structures is attributed to the imbalanced stress of distinct metal-sulfur bonds in FeMnNiVZnPS3. Interestingly, the electric field concentrates along the two sides of SSBs and gradually diminishes toward the two-dimensional (2D) plane to generate a unique electric field gradient, strongly promoting the ion-diffusion rate. Accordingly, high-entropy FeMnNiVZnPS3 demonstrates superior ion-diffusion coefficients of 10-9.7-10-8.3 cm2 s-1 and high-rate performance (311.5 mAh g-1 at 30 A g-1). This work provides an alternative way for the atomic-scale understanding and design of sophisticated HEMs, paving the way for property engineering in multi-component materials.

Stoichiometry-Tunable Synthesis and Magnetic Property Exploration of Two-Dimensional Chromium Selenides.

Emerging 2D chromium-based dichalcogenides (CrXn (X = S, Se, Te; 0 < n ≤ 2)) have provoked enormous interests due to their abundant structures, intriguing electronic and magnetic properties, excellent environmental stability, and great application potentials in next generation electronics and spintronics devices. Achieving stoichiometry-controlled synthesis of 2D CrXn is of paramount significance for such envisioned investigations. Herein, we report the stoichiometry-controlled syntheses of 2D chromium selenide (CrxSey) materials (rhombohedral Cr2Se3 and monoclinic Cr3Se4) via a Cr-self-intercalation route by designing two typical chemical vapor deposition (CVD) strategies. We have also clarified the different growth mechanisms, distinct chemical compositions, and crystal structures of the two type materials. Intriguingly, we reveal that the ultrathin Cr2Se3 nanosheets exhibit a metallic feature, while the Cr3Se4 nanosheets present a transition from p-type semiconductor to metal upon increasing the flake thickness. Moreover, we have also uncovered the ferromagnetic properties of 2D Cr2Se3 and Cr3Se4 below ∼70 K and ∼270 K, respectively. Briefly, this research should promote the stoichiometric-ratio controllable syntheses of 2D magnetic materials, and the property explorations toward next generation spintronics and magneto-optoelectronics related applications.

Phase and Composition Engineering of Self-Intercalated 2D Metallic Tantalum Sulfide for Second-Harmonic Generation.

Self-intercalation in two-dimensional (2D) materials is significant, as it offers a versatile approach to modify material properties, enabling the creation of interesting functional materials, which is essential in advancing applications across various fields. Here, we define ic-2D materials as covalently bonded compounds that result from the self-intercalation of a metal into layered 2D compounds. However, precisely growing ic-2D materials with controllable phases and self-intercalation concentrations to fully exploit the applications in the ic-2D family remains a great challenge. Herein, we demonstrated the controlled synthesis of self-intercalated H-phase and T-phase Ta1+xS2 via a temperature-driven chemical vapor deposition (CVD) approach with a viable intercalation concentration spanning from 10% to 58%. Atomic-resolution scanning transmission electron microscopy-annular dark field imaging demonstrated that the self-intercalated Ta atoms occupy the octahedral vacancies located at the van der Waals gap. The nonperiodic Ta atoms break the centrosymmetry structure and Fermi surface properties of intrinsic TaS2. Therefore, ic-2D T-phase Ta1+xS2 consistently exhibit a spontaneous nonlinear optical (NLO) effect regardless of the sample thickness and self-intercalation concentrations. Our results propose an approach to activate the NLO response of centrosymmetric 2D materials, achieving the modulation of a wide range of optoelectronic properties via nonperiodic self-intercalation in the ic-2D family.

Confinement Engineering of Zinc Single-Atom Triggered Charge Redistribution on Ruthenium Site for Alkaline Hydrogen Production.

Optimizing the interaction between metal and support in the supported metal catalysts effectively refines the electronic structure and boosts the catalytic properties of loaded active components. Herein a method is introduced to confine ultrafine ruthenium (Ru) nanoparticles within atomically dispersed Zn-N4 sites on a N-doped carbon network (Ru/Zn-N-C) through the strong electronic metal-support interaction, achieving superior catalytic activity and stability for alkaline hydrogen evolution. Spectroscopic data and theoretical modeling elucidate that the remarkable catalytic performance of Ru sites stems from their strong electronic coupling with neighboring Zn-N4 moiety and pyridinic N/pyrrolic N. This interaction induces an electron-deficient state of Ru, thereby accelerating the dissociation of H2 O and lowering the energy barriers for the desorption of OH* and H*. This insight provides a deeper understanding of the catalytic mechanisms at play. Furthermore, alkaline water electrolyzer using this catalyst as cathode delivers a mass activity of 3 A mgcat -1 at 2.0 V, much surpassing Ru-C. This research opens a novel pathway for the development of advanced materials , tailored for energy storage and conversion applications.

Atomically Unraveling Highly Crystalline Self-Intercalated Tantalum Sulfide with Correlated Stacking Registry-Dependent Magnetism.

In self-intercalated two-dimensional (ic-2D) materials, understanding the local chemical environment and the topology of the filling site remains elusive, and the subsequent correlation with the macroscopically manifested physical properties has rarely been investigated. Herein, highly crystalline gram-scale ic-2D Ta1.33S2 crystals were successfully grown by the high-pressure high-temperature method. Employing combined atomic-resolution scanning transmission electron microscopy annular dark field imaging and density functional theory calculations, we systematically unveiled the atomic structures of an atlas of stacking registries in a well-defined √3(a) × âˆš3(a) Ta1.33S2 superlattice. Ferromagnetic order was observed in the AC' stacking registry, and it evolves into an antiferromagnetic state in AA/AB/AB' stacking registries; the AA' stacking registry shows ferrimagnetic ordering. Therefore, we present a novel approach for fabricating large-scale highly crystalline ic-2D crystals and shed light on a powerful means of modulating the magnetic order of ic-2D systems via stacking engineering, i.e., stackingtronics.

Atomically Unveiling an Atlas of Polytypes in Transition-Metal Trihalides.

Transition-metal trihalides MX3 (M = Cr, Ru; X = Cl, Br, and I) belong to a family of novel two-dimensional (2D) magnets that can exhibit topological magnons and electromagnetic properties, thus affording great promises in next-generation spintronic devices. Rich magnetic ground states observed in the MX3 family are believed to be strongly correlated to the signature Kagome lattice and interlayer van der Waals coupling raised from distinct stacking orders. However, the intrinsic air instability of MX3 makes their direct atomic-scale analysis challenging. Therefore, information on the stacking-registry-dependent magnetism for MX3 remains elusive, which greatly hinders the engineering of desired phases. Here, we report a nondestructive transfer method and successfully realize an intact transfer of bilayer MX3, as evidenced by scanning transmission electron microscopy (STEM). After surveying hundreds of MX3 thin flakes, we provide a full spectrum of stacking orders in MX3 with atomic precision and calculated their associated magnetic ground states, unveiled by combined STEM and density functional theory (DFT). In addition to well-documented phases, we discover a new monoclinic C2/c phase in the antiferromagnetic (AFM) structure widely existing in MX3. Rich stacking polytypes, including C2/c, C2/m, R3̅, P3112, etc., provide rich and distinct magnetic ground states in MX3. Besides, a high density of strain soliton boundaries is consistently found in all MX3, combined with likely inverted structures, allowing AFM to ferromagnetic (FM) transitions in most MX3. Therefore, our study sheds light on the structural basis of diverse magnetic orders in MX3, paving the way for modulating magnetic couplings via stacking engineering.

Generation and Characterization of Monoclonal Antibody Against Porcine Epidemic Diarrhea Virus Nonstructural Protein 13.

Porcine epidemic diarrhea virus (PEDV) is an enteric swine coronavirus. Recent PEDV eruption in East Asian and North American countries made it notorious and caused huge economic losses to the porcine industry. Nonstructural protein 13 (nsp13) is a nucleic acid helicase/NTPase that plays a critical role in viral gene transcription and viral replication. To investigate the function of nsp13 in the context of PEDV infection, here, PEDV nsp13 gene was amplified and cloned into pET28a/pET30a/pGEX-6P-1 expression vectors. The recombinant his-tagged nsp13 and GST-tagged nsp13 were expressed. Purified his-tagged nsp13 from pET28a-nsp13 vectors was chosen for immunization. Three monoclonal antibodies (mAbs) named 5A9, 5C7, and 5G7 were identified from the hybridoma cells, and were characterized by Western blot analysis and immunofluorescent assay, which demonstrated high specificity of these three mAbs with pCAGGS-HA-nsp13. All three mAbs belong to IgG1+ kappa subclass. However, only mAb 5A9 could effectively and specifically recognize PEDV expressing nsp13. Furthermore, the generated antibody against nsp13 could be applied to investigate nsp13 function during PEDV replication.

Self-assembling behavior and interface structure in vertically aligned nanocomposite (Pr0.5Ba0.5MnO3)1-x:(CeO2)x films on (001) (La,Sr)(Al,Ta)O3 substrates.

Heteroepitaxial oxide-based nanocomposite films possessing a variety of functional properties have attracted tremendous research interest. Here, self-assembled vertically aligned nanocomposite (Pr0.5Ba0.5MnO3)1-x:(CeO2)x (x = 0.2 and 0.5) films have been successfully grown on single-crystalline (001) (La,Sr)(Al,Ta)O3 substrates by the pulsed laser deposition technique. Self-assembling behavior of the nanocomposite films and atomic-scale interface structure between Pr0.5Ba0.5MnO3 matrix and CeO2 nanopillars have been investigated by advanced electron microscopy techniques. Two different orientation relationships, (001)[100]Pr0.5Ba0.5MnO3//(001)[1-10]CeO2 and (001)[100]Pr0.5Ba0.5MnO3//(110)[1-10]CeO2, form between Pr0.5Ba0.5MnO3 and CeO2 in the (Pr0.5Ba0.5MnO3)0.8:(CeO2)0.2 film along the film growth direction, which is essentially different from vertically aligned nanocomposite (Pr0.5Ba0.5MnO3)0.5:(CeO2)0.5 films having only (001)[100]Pr0.5Ba0.5MnO3//(001)[1-10]CeO2 orientation relationship. Both coherent and semi-coherent Pr0.5Ba0.5MnO3/CeO2 interface appear in the films. In contrast to semi-coherent interface with regular distribution of interfacial dislocations, interface reconstruction occurs at the coherent Pr0.5Ba0.5MnO3/CeO2 interface. Our findings indicate that epitaxial strain imposed by the concentration of CeO2 in the nanocomposite films affects the self-assembling behavior of the vertically aligned nanocomposite (Pr0.5Ba0.5MnO3)1-x:(CeO2)x films.

B-site ordering and strain-induced phase transition in double-perovskite La2NiMnO6 films.

The magnetic and electrical properties of complex oxide thin films are closely related to the phase stability and cation ordering, which demands that we understand the process-structure-property relationships microscopically in functional materials research. Here we study multiferroic thin films of double-perovskite La2NiMnO6 epitaxially grown on SrTiO3, KTaO3, LaAlO3 and DyScO3 substrates by pulsed laser deposition. The effect of epitaxial strains imposed by the substrate on the microstructural properties of La2NiMnO6 has been systematically investigated by means of advanced electron microscopy. It is found that La2NiMnO6 films under tensile strain exhibit a monoclinic structure, while under compressive strain the crystal structure of La2NiMnO6 films is rhombohedral. In addition, by optimizing the film deposition conditions a long-range ordering of B-site cations in La2NiMnO6 films has been obtained in both monoclinic and rhombohedral phases. Our results not only provide a strategy for tailoring phase stability by strain engineering, but also shed light on tuning B-site ordering by controlling film growth temperature in double-perovskite La2NiMnO6 films.