Control of the Phase Distribution in TMDs by Strain Engineering and Kirigami Techniques.

Materials exhibiting both metallic and semiconducting states, including two-dimensional transition metal dichalcogenides (TMDs), have numerous applications. We therefore investigate the effects of axial and shear strains on the phase energetics of pristine and striped TMDs using density functional theory and classical molecular dynamics simulations. We demonstrate that control of the phase distribution can be achieved by the integration of strain engineering and Kirigami techniques.

Tunnel barriers for Fe-based spin valves providing high spin-polarized current.

Employing density functional theory for ground state quantum mechanical calculations and the non-equilibrium Green's function method for transport calculations, we investigate the potential of CdS, ZnS, CdZnS, and ZnCdS as tunnel barriers in magnetic tunnel junctions for spintronics. Based on the finding that the valence band edges of these semiconductors are dominated by p orbitals and the conduction band edges by s orbitals, we show that symmetry filtering of the Bloch states in magnetic tunnel junctions with Fe electrodes results in high tunneling magnetoresistances and high spin-polarized current (up to two orders of magnitude higher than in the case of the Fe/MgO/Fe magnetic tunnel junction).

Controllable -Polarized Spin Current in Artificially Structured Ferromagnetic Oxide with Strong Spin-Orbit Coupling.

Realizing field-free switching of perpendicular magnetization by spin-orbit torques is crucial for developing advanced magnetic memory and logic devices. However, existing methods often involve complex designs or hybrid approaches, which complicate fabrication and affect device stability and scalability. Here, we propose a novel approach using -polarized spin currents for deterministic switching of perpendicular magnetization through interfacial engineering.

Ultraflat Cu(111) foils by surface acoustic wave-assisted annealing.

Ultraflat metal foils are essential for semiconductor nanoelectronics applications and nanomaterial epitaxial growth. Numerous efforts have been devoted to metal surface engineering studies in the past decades. However, various challenges persist, including size limitations, polishing non-uniformities, and undesired contaminants.

Vertical heterostructure of graphite-MoS for gas sensing.

2D materials, given their form-factor, high surface-to-volume ratio, and chemical functionality have immense use in sensor design. Engineering 2D heterostructures can result in robust combinations of desirable properties but sensor design methodologies require careful considerations about material properties and orientation to maximize sensor response. This study introduces a sensor approach that combines the excellent electrical transport and transduction properties of graphite film with chemical reactivity derived from the edge sites of semiconducting molybdenum disulfide (MoS) through a two-step chemical vapour deposition method.

All van der Waals Semiconducting PtSe Field Effect Transistors with Low Contact Resistance Graphite Electrodes.

Contact resistance is a multifaceted challenge faced by the 2D materials community. Large Schottky barrier heights and gap-state pinning are active obstacles that require an integrated approach to achieve the development of high-performance electronic devices based on 2D materials. In this work, we present semiconducting PtSe field effect transistors with all-van-der-Waals electrode and dielectric interfaces.

A robust thin-film droplet-induced electricity generator.

The pursuit of cost-effective, high-voltage electricity generators activated by droplets represents a new frontier in hydropower technology. This study presents an economical method for crafting droplet generators using common materials such as solid polytetrafluoroethylene (PTFE) films and readily available tapes, eliminating the need for specialized cleanroom facilities. A thorough investigation into voltage-limiting factors, encompassing device capacitance and induced electrode charges, reveals specific areas with potential for optimization.

Biobased Interpenetrating Polymer Network Membranes for Sustainable Molecular Sieving.

There is an urgent need for sustainable alternatives to fossil-based polymer materials. Through nanodomain engineering, we developed, without using toxic cross-linking agents, interpenetrating biopolymer network membranes from natural compounds that have opposing polarity in water. Agarose and natural rubber latex were consecutively self-assembled and self-cross-linked to form patchlike nanodomains.

Observation of a Higher-Order End Topological Insulator in a Real Projective Lattice.

The modern theory of quantized polarization has recently extended from 1D dipole moment to multipole moment, leading to the development from conventional topological insulators (TIs) to higher-order TIs, i.e., from the bulk polarization as primary topological index, to the fractional corner charge as secondary topological index.

Potential of AlP and GaN as barriers in magnetic tunnel junctions.

AlP and GaN are wide band gap semiconductors used industrially in light emitting diodes. We investigate their potential as tunnel barriers in magnetic tunnel junctions, employing density functional theory and the non-equilibrium Green's function method for ground state and quantum transport calculations, respectively. We show that the valence band edges are dominated by p orbitals and the conduction band edges are dominated by s orbitals.

Bandgap Engineering of Melon using Highly Reduced Graphene Oxide for Enhanced Photoelectrochemical Hydrogen Evolution.

The uncondensed form of polymeric carbon nitrides (PCN), generally known as melon, is a stacked 2D structure of poly(aminoimino)heptazine. Melon is used as a photocatalyst in solar energy conversion applications, but suffers from poor photoconversion efficiency due to weak optical absorption in the visible spectrum, high activation energy, and inefficient separation of photoexcited charge carriers. Experimental and theoretical studies are reported to engineer the bandgap of melon with highly reduced graphene oxide (HRG).

Graphene foam membranes with tunable pore size for next-generation reverse osmosis water desalination.

The development of carbon-based reverse osmosis membranes for water desalination is hindered by challenges in achieving a high pore density and controlling the pore size. We use molecular dynamics simulations to demonstrate that graphene foam membranes with a high pore density provide the possibility to tune the pore size by applying mechanical strain. As the pore size is found to be effectively reduced by a structural transformation under strain, graphene foam membranes are able to combine perfect salt rejection with unprecedented water permeability.

ZnSe and ZnTe as tunnel barriers for Fe-based spin valves.

Owing to their use in the optoelectronic industry, we investigate whether ZnSe and ZnTe can be utilised as tunnel barrier materials in magnetic spin valves. We perform electronic structure and linear response transport calculations based on self-interaction-corrected density functional theory for both Fe/ZnSe/Fe and Fe/ZnTe/Fe junctions. In the Fe/ZnSe/Fe junction the transport is tunneling-like and a symmetry-filtering mechanism is at play, implying that only the majority spin electrons with symmetry are transmitted with large probability, resulting in a potentially large tunneling magnetoresistance (TMR) ratio.

Inhibitor and Activator: Dual Role of Subsurface Sulfide Enables Selective and Efficient Electro-Oxidation of Methanol to Formate on CuS@CuO Core-Shell Nanosheet Arrays.

Selective electro-oxidation of aliphatic alcohols into value-added carboxylates at lower potentials than that of the oxygen evolution reaction (OER) is an environmentally and economically desirable anode reaction for clean energy storage and conversion technologies. However, it is challenging to achieve both high selectivity and high activity of the catalysts for the electro-oxidation of alcohols, such as the methanol oxidation reaction (MOR). Herein, a monolithic CuS@CuO/copper-foam electrode for the MOR with superior catalytic activity and almost 100% selectivity for formate is reported.

Ti C T MXene van der Waals Gate Contact for GaN High Electron Mobility Transistors.

Gate controllability is a key factor that determines the performance of GaN high electron mobility transistors (HEMTs). However, at the traditional metal-GaN interface, direct chemical interaction between metal and GaN can result in fixed charges and traps, which can significantly deteriorate the gate controllability. In this study, Ti C T MXene films are integrated into GaN HEMTs as the gate contact, wherein van der Waals heterojunctions are formed between MXene films and GaN without direct chemical bonding.

(LaCrO) /SrCrO superlattices as transparent p-type semiconductors with finite magnetization.

The electronic and magnetic properties of (LaCrO) /SrCrO superlattices are investigated using first principles calculations. We show that the magnetic moments in the two CrO layers sandwiching the SrO layer compensate each other for even but give rise to a finite magnetization for odd , which is explained by charge ordering with Cr and Cr ions arranged in a checkerboard pattern. The Cr ions induce in-gap hole states at the interface, implying that the transparent superlattices are p-type semiconductors.

Preferential Pyrolysis Construction of Carbon Anodes with 8400 h Lifespan for High-Energy-Density K-ion Batteries.

Carbonaceous materials are promising anodes for practical potassium-ion batteries, but fail to meet the requirements for durability and high capacities at low potentials. Herein, we constructed a durable carbon anode for high-energy-density K-ion full cells by a preferential pyrolysis strategy. Utilizing S and N volatilization from a π-π stacked supermolecule, the preferential pyrolysis process introduces low-potential active sites of sp hybridized carbon and carbon vacancies, endowing a low-potential "vacancy-adsorption/intercalation" mechanism.

Nanostructured Gallium Nitride Membrane at Wafer Scale for Photo(Electro)catalytic Polluted Water Remediation.

Photo(electro)catalysis methods have drawn significant attention for efficient, energy-saving, and environmental-friendly organic contaminant degradation in wastewater. However, conventional oxide-based powder photocatalysts are limited to UV-light absorption and are unfavorable in the subsequent postseparation process. In this paper, a large-area crystalline-semiconductor nitride membrane with a distinct nanoporous surface is fabricated, which can be scaled up to a full wafer and easily retrieved after photodegradation.

Experimental Identification of the Second-Order Non-Hermitian Skin Effect with Physics-Graph-Informed Machine Learning.

Topological phases of matter are conventionally characterized by the bulk-boundary correspondence in Hermitian systems. The topological invariant of the bulk in d dimensions corresponds to the number of (d - 1)-dimensional boundary states. By extension, higher-order topological insulators reveal a bulk-edge-corner correspondence, such that nth order topological phases feature (d - n)-dimensional boundary states.

Lattice Instability and Ultralow Lattice Thermal Conductivity of Layered PbIF.

Understanding the interplay between various design strategies (for instance, bonding heterogeneity and lone pair induced anharmonicity) to achieve ultralow lattice thermal conductivity (κ) is indispensable for discovering novel functional materials for thermal energy applications. In the present study, we investigate layered PbXF (X = Cl, Br, I), which offers bonding heterogeneity through the layered crystal structure, anharmonicity through the Pb 6s lone pair, and phonon softening through the mass difference between F and Pb/X. The weak interlayer van der Waals bonding and the strong intralayer ionic bonding with partial covalent bonding result in a significant bonding heterogeneity and a poor phonon transport in the out-of-plane direction.

Morphology-Control Growth of Graphene Islands by Nonlinear Carbon Supply.

Controlling the morphology of graphene and other 2D materials in chemical vapor deposition (CVD) growth is crucial because the morphology reflects the crystal quality of as-synthesized nanomaterials in a certain way, and consequently it indirectly represents the physical properties of 2D materials such as bandgap, selective ion transportation, and impermeability. However, precise control of the morphology is limited by the complex formation mechanism and sensitive growth-environment factors of graphene. Therefore, the CVD synthesis of single-crystal hexagonal-shaped graphene islands with specific sizes is challenging.

Large Spin Coherence Length and High Photovoltaic Efficiency of the Room Temperature Ferrimagnet Ca FeOsO by Strain Engineering.

The influence of epitaxial strain on the electronic, magnetic, and optical properties of the distorted double perovskite Ca FeOsO is studied. These calculations show that the compound realizes a monoclinic structure with P2 /n space group from -6% to +6% strain. While it retains ferrimagnetic ordering with a net magnetic moment of 2 μ per formula unit at low strain, it undergoes transitions into E-antiferromagnetic and C-antiferromagnetic phases at -5% and +5% strain, respectively.