Phase-Selective Synthesis of Rhombohedral WS Multilayers by Confined-Space Hybrid Metal-Organic Chemical Vapor Deposition.

Rhombohedral polytype transition metal dichalcogenide (TMDC) multilayers exhibit non-centrosymmetric interlayer stacking, which yields intriguing properties such as ferroelectricity, a large second-order susceptibility coefficient χ, giant valley coherence, and a bulk photovoltaic effect. These properties have spurred significant interest in developing phase-selective growth methods for multilayer rhombohedral TMDC films. Here, we report a confined-space, hybrid metal-organic chemical vapor deposition method that preferentially grows 3R-WS multilayer films with thickness up to 130 nm.

Chemically Tailored Growth of 2D Semiconductors via Hybrid Metal-Organic Chemical Vapor Deposition.

Two-dimensional (2D) semiconducting transition-metal dichalcogenides (TMDCs) are an exciting platform for excitonic physics and next-generation electronics, creating a strong demand to understand their growth, doping, and heterostructures. Despite significant progress in solid-source (SS-) and metal-organic chemical vapor deposition (MOCVD), further optimization is necessary to grow highly crystalline 2D TMDCs with controlled doping. Here, we report a hybrid MOCVD growth method that combines liquid-phase metal precursor deposition and vapor-phase organo-chalcogen delivery to leverage the advantages of both MOCVD and SS-CVD.

Biaxial Tensile Strain Enhances Electron Mobility of Monolayer Transition Metal Dichalcogenides.

Strain engineering can modulate the properties of two-dimensional (2D) semiconductors for electronic and optoelectronic applications. Recent theory and experiments have found that uniaxial tensile strain can improve the electron mobility of monolayer MoS, a 2D semiconductor, but the effects of biaxial strain on charge transport are not well characterized in 2D semiconductors. Here, we use biaxial tensile strain on flexible substrates to probe electron transport in monolayer WS and MoS transistors.

Recent and emerging trends of metal-organic frameworks (MOFs)-based sensors for detecting food contaminants: A critical and comprehensive review.

Interest in the use of sensors based on metal-organic frameworks (MOFs) to detect food pollutants has been growing recently due to the desirable characteristics of MOFs, including uniform structures, large surface area, ultrahigh porosity and easy-to-functionalize surface. Fundamentally, this review offers an excellent solution using MOFs-based sensors (e.g.

A Novel Indicator Based on Polyacrylamide Hydrogel and Bromocresol Green for Monitoring the Total Volatile Basic Nitrogen of Fish.

An intelligent indicator was developed by immobilizing bromocresol green (BCG) within the polyacrylamide (PAAm) hydrogel matrix to monitor the total volatile basic nitrogen (TVB-N) content of fish. The FTIR analysis indicated that BCG was effectively incorporated into the PAAm through the formation of intermolecular hydrogen bonds. A thermogravimetric analysis (TGA) showed that the PAAm/BCG indicator had a mere 0.

Origin of static magnetic field induced quality improvement in sea bass () during cold storage: Microbial growth inhibition and protein structure stabilization.

To explore the potential application of static magnetic field (SMF) treatment in marine fish preservation, the sea bass () was exposed to SMF (5 mT) and its quality changes during cold storage were evaluated by total viable counts, water holding capacity, pH, color, and textural properties. Characteristics of the protein in the presence of SMF were investigated by measuring total sulfhydryl (SH) content, Ca-ATPase activity, secondary structure, and muscle microstructure. SMF treatment exhibited positive effects on fish quality, showing favorable performance on the most quality indicators, especially a significant reduction in the Microbial Counts.

Emerging Approach for Fish Freshness Evaluation: Principle, Application and Challenges.

Affected by micro-organisms and endogenous enzymes, fish are highly perishable during storage, processing and transportation. Efficient evaluation of fish freshness to ensure consumer safety and reduce raw material losses has received an increasing amount of attention. Several of the conventional freshness assessment techniques have plenty of shortcomings, such as being destructive, time-consuming and laborious.

Polysaccharides confer benefits in immune regulation and multiple sclerosis by interacting with gut microbiota.

Pharmacological and clinical studies have consistently demonstrated that polysaccharides exhibit great potential on immune regulation. Polysaccharides can interact directly or indirectly with the immune system, triggering cell-cell communication and molecular recognition, leading to immunostimulatory responses. Gut microbiota is adept at foraging polysaccharides as energy sources and confers benefits in the context of immunity and chronic autoimmune disease, such as multiple sclerosis.

Bandgap control in two-dimensional semiconductors via coherent doping of plasmonic hot electrons.

Bandgap control is of central importance for semiconductor technologies. The traditional means of control is to dope the lattice chemically, electrically or optically with charge carriers. Here, we demonstrate a widely tunable bandgap (renormalisation up to 550 meV at room-temperature) in two-dimensional (2D) semiconductors by coherently doping the lattice with plasmonic hot electrons.

Out-of-Plane Deformations Determined Mechanics of Vanadium Disulfide (VS) Sheets.

The rapid development of two-dimensional (2D) materials has significantly broadened the scope of 2D science in both fundamental scientific interests and emerging technological applications, wherein the mechanical properties play an indispensably key role. Nevertheless, particularly challenging is the ultrathin nature of 2D materials that makes their manipulations and characterizations considerably difficult. Herein, thanks to the excellent flexibility of vanadium disulfide (VS) sheets, their susceptibility to out-of-plane deformation is exploited to realize the controllable loading and enable the accurate measurements of mechanical properties.

Multifunctional superhydrophobic adsorbents by mixed-dimensional particles assembly for polymorphic and highly efficient oil-water separation.

Supra-wetting materials, especially superhydrophobic absorption materials, as an emerging advanced oil-water separation material have attracted extensive concern in the treatment of oil spillage and industrial oily wastewater. However, it is still a challenge to fabricate robust and multifunctional superhydrophobic materials for the multitasking oil-water separation and fast clean-up of the viscous crude oil by an environment-friendly and scalable method. Herein, a solid-solid phase ball-milling strategy without chemical reagent-free modification was proposed to construct heterogeneous superhydrophobic composites by using waste soot as the solid-phase superhydrophobic modifier.

Epitaxial Growth of Centimeter-Scale Single-Crystal MoS Monolayer on Au(111).

Two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) have emerged as attractive platforms in next-generation nanoelectronics and optoelectronics for reducing device sizes down to a 10 nm scale. To achieve this, the controlled synthesis of wafer-scale single-crystal TMDs with high crystallinity has been a continuous pursuit. However, previous efforts to epitaxially grow TMD films on insulating substrates (, mica and sapphire) failed to eliminate the evolution of antiparallel domains and twin boundaries, leading to the formation of polycrystalline films.

Revealing Strong Plasmon-Exciton Coupling between Nanogap Resonators and Two-Dimensional Semiconductors at Ambient Conditions.

Strong coupling of two-dimensional semiconductor excitons with plasmonic resonators enables control of light-matter interaction at the subwavelength scale. Here we develop such strong coupling in plasmonic nanogap resonators, which allows modification of exciton strength by altering electromagnetic environments in nearby semiconductor monolayers. Using this system, we not only demonstrate a large vacuum Rabi splitting up to 163 meV and splitting features in photoluminescence spectra but also reveal that the effective exciton number contributing to the coupling can be reduced down to the single-digit level (N<10), which is 2 orders lower than that of previous systems, close to single-exciton based strong coupling.

Scalable Production of Two-Dimensional Metallic Transition Metal Dichalcogenide Nanosheet Powders Using NaCl Templates toward Electrocatalytic Applications.

Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs) have attracted tremendous interest due to their intriguing physical properties and broad application potential. However, batch production of high-quality 2D MTMDCs based on existing synthesis on 2D surfaces remains a huge challenge. Herein, a universal synthetic route for the scalable synthesis of high-quality 2D MTMDC (e.

Chemical Vapor Deposition Grown Large-Scale Atomically Thin Platinum Diselenide with Semimetal-Semiconductor Transition.

Among two-dimensional (2D) transition-metal dichalcogenides (TMDCs), platinum diselenide (PtSe) stands in a distinct place due to its fancy transition from type-II Dirac semimetal to semiconductor with a thickness variation from bulk to monolayer (1 ML) and the related versatile applications especially in mid-infrared detectors. However, achieving atomically thin PtSe is still a challenging issue. Herein, we have designed a facile chemical vapor deposition (CVD) method to achieve the synthesis of atomically thin 1T-PtSe on an electrode material of Au foil.

Thickness Tunable Wedding-Cake-like MoS Flakes for High-Performance Optoelectronics.

Atomically thin transition-metal dichalcogenides (TMDCs) have received substantial interest due to their typical thickness-dependent optical and electronic properties and related applications in optoelectronics. However, the large-scale, thickness-tunable growth of such materials is still challenging. Herein, we report a fast growth of thickness-tunable wedding-cake-like MoS flakes on 6-in.

Thinnest Nonvolatile Memory Based on Monolayer h-BN.

2D materials have attracted much interest over the past decade in nanoelectronics. However, it was believed that the atomically thin layered materials are not able to show memristive effect in vertically stacked structure, until the recent discovery of monolayer transition metal dichalcogenide (TMD) atomristors, overcoming the scaling limit to sub-nanometer. Herein, the nonvolatile resistance switching (NVRS) phenomenon in monolayer hexagonal boron nitride (h-BN), a typical 2D insulator, is reported.

Tunable Valley Polarized Plasmon-Exciton Polaritons in Two-Dimensional Semiconductors.

Monolayers of transition-metal dicalcogenides have emerged as two-dimensional semiconductors with direct bandgaps at degenerate but inequivalent electronic "valleys", supporting distinct excitons that can be selectively excited by polarized light. These valley-addressable excitons, when strongly coupled with optical resonances, lead to the formation of half-light half-matter quasiparticles, known as polaritons. Here we report self-assembled plasmonic crystals that support tungsten disulfide monolayers, in which the strong coupling of semiconductor excitons and plasmon lattice modes results in a Rabi splitting of ∼160 meV in transmission spectra as well as valley-polarized photoluminescence at room temperature.

Recent progress in the controlled synthesis of 2D metallic transition metal dichalcogenides.

Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDCs), the complement of 2D semiconducting TMDCs, have attracted extensive attentions in recent years because of their versatile properties such as superconductivity, charge density wave, and magnetism. To promote the investigations of their fantastic properties and broad applications, the preparation of large-area, high-quality, and thickness-tunable 2D MTMDCs has become a very urgent topic and great efforts have been made. This topical review therefore focuses on the introduction of the recent achievements for the controllable syntheses of 2D MTMDCs (VS, VSe, TaS, TaSe, NbS, NbSe, etc).

Chemical Vapor Deposition Grown Wafer-Scale 2D Tantalum Diselenide with Robust Charge-Density-Wave Order.

2D metallic transition metal dichalcogenides (MTMDCs) are benchmark systems for uncovering the dimensionality effect on fascinating quantum physics, such as charge-density-wave (CDW) order, unconventional superconductivity, and magnetism, etc. However, the scalable and thickness-tunable syntheses of such envisioned MTMDCs are still challenging. Meanwhile, the origin of CDW order at the 2D limit is controversial.

Epitaxial Growth of Two-Dimensional Metal-Semiconductor Transition-Metal Dichalcogenide Vertical Stacks (VSe/MX) and Their Band Alignments.

Two-dimensional (2D) metal-semiconductor transition-metal dichalcogenide (TMDC) vertical heterostructures play a crucial role in device engineering and contact tuning fields, while their direct integration still challenging. Herein, a robust epitaxial growth method is designed to construct multiple lattice-matched 2D metal-semiconductor TMDC vertical stacks (VSe/MX, M: Mo, W; X: S, Se) by a two-step chemical vapor deposition method. Intriguingly, the metallic VSe preferred to nucleate and extend from the energy-favorable edge site of the semiconducting MX underlayer to form VSe/MX vertical heterostructures.

Na-assisted fast growth of large single-crystal MoS on sapphire.

Monolayer molybdenum sulfide (MoS), a typical semiconducting transition metal dichalcogenide, has emerged as a perfect platform for next-generation electronics and optoelectronics due to its sizeable band gap and strong light-matter interactions. Nevertheless, the controlled growth of a monolayer MoS single-crystal with a large-domain size and high crystal quality still faces great challenges. Herein, we demonstrate the fast growth of a large-domain monolayer MoS on the c-plane sapphire substrate with the assistance of sodium chloride (NaCl) crystals as the intermediate promoter.

Identifying the Non-Identical Outermost Selenium Atoms and Invariable Band Gaps across the Grain Boundary of Anisotropic Rhenium Diselenide.

Rhenium diselenide (ReSe) is a unique transition-metal dichalcogenide (TMDC) possessing distorted 1T structure with a triclinic symmetry, strong in-plane anisotropy, and promising applications in optoelectronics and energy-related fields. So far, the structural and physical properties of ReSe are mainly uncovered by transmission electron microscopy and spectroscopy characterizations. Herein, by combining scanning tunneling microscopy and spectroscopy (STM and STS) with first-principles calculations, we accomplish the on-site atomic-scale identification of the top four non-identical Se atoms in a unit cell of the anisotropic monolayer ReSe on the Au substrate.