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Schottky diode is the fundamental building blocks for modern electronics and optoelectronics. Reducing the semiconductor layer thickness could shrink the vertical size of a Schottky diode, improving its speed and integration density. Here, we demonstrate a new approach to fabricate a Schottky diode with ultrashort physical length approaching atomic limit. By mechanically laminating prefabricated metal electrodes on both-sides of two-dimensional MoS2, the intrinsic metal–semiconductor interfaces can be well retained. As a result, we demonstrate the thinnest Schottky diode with a length of 2.6 nm and decent rectification behavior. Furthermore, with a diode length smaller than the semiconductor depletion length, the carrier transport mechanisms are investigated and explained by thickness-dependent and temperature-dependent electrical measurements. Our study not only pushes the scaling limit of a Schottky diode but also provides a general double-sided electrodes integration approach for other ultrathin vertical devices.

Two-dimensional van der Waals heterostructures (vdWHs) have attracted considerable interest1–4. However, most vdWHs reported so far  are created by an arduous micromechanical exfoliation and manual restacking process5, which—although versatile for proof-of-concept demonstrations6–16and fundamental studies17–30—is clearly not scalable for practical technologies. Here we report a general synthetic strategy for two-dimensional vdWH arrays between metallic transition-metal dichalcogenides (m-TMDs) and semiconducting TMDs (s-TMDs). By selectively patterning nucleation sites on monolayer or bilayer s-TMDs, we precisely control the nucleation and growth of diverse m-TMDs with designable periodic arrangements and tunable lateral dimensions at the predesignated spatial locations, producing a series of vdWH arrays, including VSe2/WSe2, NiTe2/WSe2, CoTe2/WSe2, NbTe2/WSe2, VS2/WSe2, VSe2/MoS2and VSe2/WS2. Systematic scanning transmission electron microscopy studies reveal nearly ideal vdW interfaces with widely tunable moiré superlattices. With the atomically clean vdW interface, we further show that the m-TMDs function as highly reliable synthetic vdW contacts for the underlying WSe2with excellent device performance and yield, delivering a high ON-current density of up to 900 microamperes per micrometre in bilayer WSe2transistors. This general synthesis of diverse two-dimensional vdWH arrays provides a versatile material platform for exploring exotic physics and promises a scalable pathway to high-performance devices.

Considering the importance of gene expression studies for understanding the biology of glioma stem cells (GSCs), we aimed to identify the reliable reference genes in GSCs that were derived from the glioma cell lines T98G, LN229, 090116 and 091214. Quantitative real-time reverse-transcription PCR was employed using 11 reference genes identified through a PubMed literature search, and the assessment of stability through the geNorm, Normfinder and coefficient of variation methods was performed to select suitable reference genes. We found that HPRT1and RPL13Awere the most suitable reference genes, and validated the geometric mean of these genes to normalize the expression of stemness genes by GSCs. Therefore, it is necessary to select novel cell-specific reference genes with greater expression stability for gene expression studies in GSCs.

Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDs) have recently drawn increasing interest for fundamental studies and potential applications in catalysis, charge density wave (CDW), interconnections, spin-torque devices, as well superconductors. Despite some initial efforts, the thickness-tunable synthesis of atomically thin MTMDs remains a considerable challenge. Here we report controlled synthesis of 2D cobalt telluride (CoTe2) nanosheets with tunable thickness using an atmospheric pressure chemical vapor deposition (APCVD) approach and investigate their thickness-dependent electronic properties. The resulting nanosheets show a well-faceted hexagonal or triangular geometry with a lateral dimension up to ∼200 μm. Systematic studies of growth at varying growth temperatures or flow rates demonstrate that nanosheets thickness is readily tunable from over 30 nm down to 3.1 nm. X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution scanning transmission electron microscope (STEM) studies reveal the obtained CoTe2nanosheets are high-quality single crystals in the hexagonal 1T phase. Electrical transport studies show the 2D CoTe2nanosheets display excellent electrical conductivities up to 4.0 × 105S m–1and very high breakdown current densities up to 2.1 × 107A/cm2, both with strong thickness tunability.

Two-dimensional (2D) layered materials have stimulated extensive research interest for their unique thickness-dependent electronic and optical properties. However, the layer-number-dependent studies on 2D materials to date are largely limited to exfoliated flakes with relatively small lateral size and poor yield. The direct synthesis of 2D materials with a precise control of the number of atomic layers remains a substantial synthetic challenge. Here we report a systematic study of chemical vapor deposition synthesis of large-area atomically thin 2D nickel telluride (NiTe2) single crystals and investigate the thickness dependent electronic properties. By controlling the growth temperature, we show that the highly uniform NiTe2single crystals can be synthesized with precisely tunable thickness varying from 1, 2, 3, . . . to multilayers with a standard deviation (∼0.3 nm) of less than the thickness of a monolayer layer NiTe2. Our studies further reveal a systematic evolution of single crystal domain size and nucleation density with the largest lateral domain size up to ∼440 μm. X-ray diffraction, transmission electron microscopy, and high resolution scanning transmission electron microscope studies demonstrate that the resulting 2D crystals are high quality single crystals and adopt hexagonal 1T phase. Electrical transport studies reveal that the 2D NiTe2single crystals show a strong thickness-tunable electrical properties, with an excellent conductivity up to 7.8 × 105S m–1and extraordinary breakdown current density up to 4.7 × 107A/cm2. The systematic study and robust synthesis of NiTe2nanosheets defines a reliable chemical route to 2D single crystals with precisely tailored thickness and could enable the design of new device architectures based on thickness-tunable electrical properties.

Graphical Abstract: The N-doped MOF-derived bimetallic phosphides catalysts with superior catalytic activities were synthesized using an oil bath plus solvothermal approach. An extremely low overpotential of 290.0 ± 2.4 mV at 10 mA cm−2and Tafel slope of 60.85 mV dec−1were achieved based on the N-Ni2Co3-P catalysts.

Developing next-generation high-energy–density rechargeable batteries is pivotal to solve the growing demand for sustainable energy. Lithium metal battery (LMB) is the representative in post-lithium-ion battery era. However, uncontrollable growth of Li dendrites and low Coulombic efficiency (CE) prevent it from practical applications in LMBs. Here, a multifunctional tantalum oxide nanosheets/polypropylene (TaO3@PP) composite separator is developed to regulating ion transport in atomic scale. The TaO3coating can improve the wettability and thermal stability of the PP separator. The openings of the nanomesh structure provide Li+channels to allow efficient lithium-ion transport. The electrostatic attraction force between TaO3nanosheets and Li+and the electrostatic repulsion force between TaO3nanosheets and anions ensuring the fast Li+diffusion and low concentration polarization. The TaO3@PP separator can regulate Li+distribution and promote uniform lithium deposition, inhibiting the Li dendrite growth. Thus, the composite separator achieves a high Li-ion transference number of 0.72. The LiFePO4||Li cell with the composite separator delivers high discharge capacity of 145 mAh g−1over 500 cycles at 0.5 C.

Background Information:Previous studies have revealed that leptin may be involved in epithelial-mesenchymal transition (EMT), a crucial initiator of cancer progression to facilitate metastatic cascade, increase tumor recurrence, and ultimately cause poor prognosis. However, the underlying mechanism remains unclear. The aim of our present study was to investigate the effect of leptin on EMT of breast cancer cells and the underlying mechanism. Results:Our data demonstrated that leptin significantly increased the phosphorylation of STAT3, Akt, and ERK1/2, elevated the expression of IL-8, and induced breast cancer cells to undergo EMT. The effect of leptin on IL-8 could visibly abolished by the inhibitor of PI3K LY294002. In addition, leptin-induced EMT of breast cancer cells was blocked by anti-IL-8 antibodies. Examination of the expression of ObR, leptin, IL-8 and EMT-related biomarkers in patient specimens demonstrated that malignant breast carcinoma with lymph node metastases (LNM), which represents poor prognosis, expressed higher levels of ObR, leptin, IL-8 than other types of breast cancer, and displayed more obvious EMT transversion. In vivoxenograft experiment revealed that leptin signally promoted tumor growth and metastasis and increased the expressions of IL-8 and EMT-related biomarkers. Conclusions:Our results support that leptin-induced EMT in breast cancer cells requires IL-8 activation via the PI3K/Akt signal pathway.