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Two-dimensional (2D) materials have been identified as promising candidates for future electronic devices. However, high dielectric constant (κ) materials, which can be integrated with 2D semiconductors, are still rare. Here, we report a hydrate-assisted thinning chemical vapor deposition (CVD) technique to grow manganese oxide (Mn3O4) single crystal nanosheets, enabled by a strategy to minimize the substrate lattice mismatch and control the growth kinetics. The material demonstrated a dielectric constant up to 135, an equivalent oxide thickness (EOT) as low as 0.8 nm, and a breakdown field strength (Ebd) exceeding 10 MV/cm. MoS2 field-effect transistors (FETs) integrated with Mn3O4 thin films through mechanical stacking method operate under low voltages (<1 V), achieving a near 108 Ion/Ioff ratio and a subthreshold swing (SS) as low as 84 mV/dec. The MoS2 FET exhibit nearly zero hysteresis (<2 mV/MV cm⁻¹) and a low drain-induced barrier lowering (~20 mV/V). This work further expands the family of 2D high-κ dielectric materials and provides a feasible exploration for the epitaxial growth of single-crystal thin films of non-layered materials. High dielectric constant (κ) materials compatible with van der Waals materials are desired to promote the development of 2D electronics. Here, the authors report a method to grow Mn3O4 nanosheets exhibiting κ up to 135 and equivalent oxide thickness down to 0.8 nm, enabling the fabrication of high-performance 2D MoS2 transistors. [ABSTRACT FROM AUTHOR]

In this study, we successfully synthesized high-quality 2D layered BiOI crystals using a novel space-confined molten salt method. These crystals exhibit a bandgap of 1.9 eV, closely aligning with theoretical expectations. The photodetectors fabricated from these BiOI nanosheets demonstrate exceptional ultraviolet (UV) detection capabilities. Key performance metrics include an ultrahigh photoresponsivity of 1048 mA W−1, an impressive external quantum efficiency of 420%, and a significant detectivity of 4.7 × 1012 Jones, coupled with a fast response time of 420/690 μs at 310 nm. This study not only highlights the potential of BiOI in UV photodetectors but also marks a substantial advancement in the development of high-performance bismuth-based semiconductor optoelectronic devices. [ABSTRACT FROM AUTHOR]

Advancing next-generation electronics necessitates precise control of dielectric properties in 2D materials. Here, the first synthesis of novel 2D quasi-van der Waals (vdW) europium oxysulfur (Eu 2 SO x ) compounds, comprising hexagonal Eu₂SO₂ and tetragonal Eu₂SO₆ phases, with composition-tunable dielectric properties, is presented. Using a homodiffusive-controlled epitaxial growth method, materials are achieved with complementary characteristics: the hexagonal Eu₂SO₂ phase exhibits a high dielectric constant (≈30) paired with a moderate bandgap (≈4.56 eV), while the tetragonal Eu₂SO₆ phase offers a wider bandgap (≈5.62 eV) but a lower dielectric constant (≈20). The potential of these materials is demonstrated by integrating ultrathin Eu₂SO₂ nanoplates with molybdenum disulfide (MoS₂) field-effect transistors (FETs) via vdW forces. The resulting devices achieve a near-ideal I on /I off ratio (≈10⁸), minimal hysteresis (≈5.3 mV), a low subthreshold slope (≈63.5 mV dec⁻¹), and ultralow leakage current (≈10⁻¹⁴ A). These results highlight the capacity of europium oxysulfur compounds to address the trade-off between dielectric constant and bandgap, offering tailored solutions for diverse 2D electronic applications. This work underscores the potential of composition engineering to expand the family of rare-earth oxysulfur compounds for nanoelectronics, paving the way for innovative gate dielectrics in next-generation devices., (© 2025 Wiley‐VCH GmbH.)

The development of dielectrics with atomic planes and van der Waals (vdW) interfaces is essential for enhancing the performance of 2D devices. However, vdW dielectrics often have smaller bandgaps compared to traditional 3D dielectrics, limiting their options. This study introduces AZBX (AZn₂BO₃X₂, where A = K or Rb, X = Cl or Br), a nonlinear deep-ultraviolet optical crystal, as a quasi-vdW layered dielectric ideal for 2D electronic devices. Focusing on KZBB, it's excellent dielectric properties, including a wide bandgap, high dielectric constant (high-κ), and smooth interfaces are demonstrated. When used as the top gate dielectric in a KZBB/MoS₂ field-effect transistor (FET) with MoS₂ channels and graphene contacts, the device exhibits outstanding performance, with a steep subthreshold swing (≈ 73 mV dec -1 ), high on/off ratio (≈ 10⁷), negligible hysteresis (0-8 mV), and stable, low leakage current (≈10⁻⁷ A cm - 2 ) before breakdown. This work expands the 2D material and dielectric landscape and highlights the strong potential of AZBX as high-performance dielectrics., (© 2024 Wiley‐VCH GmbH.)

The alkaline hydrogen evolution reaction (HER) is limited by scarce proton availability, resulting in slower reaction kinetics compared to those under acidic conditions. Enhancing the local chemical environment of protons on the catalyst surface can improve the intrinsic reaction kinetics. Here, we design a Mo/MoO 2 metallic heterojunction that creates an acidic-like environment with a proton-rich surface, significantly enhancing HER performance in alkaline electrolytes, as confirmed by in situ spectroscopy and electrochemical analysis. A self-standing Mo/MoO 2 catalytic electrode is fabricated via a controlled pyrolysis-reduction strategy. This electrode exhibits exceptional HER activity, with low overpotentials of 65 mV at 10 mA cm -2 and 315 mV at 500 mA cm -2 , a Tafel slope of 38.2 mV dec -1 , and stability exceeding 60 h at -300 mA cm -2 in alkaline solution. The porous flake array structure of the Mo/MoO 2 heterojunctions enhances the adjacent hydronium (H 3 O + ) concentration, resulting in a Δ G H* value of 0.15 eV and a water dissociation energy barrier of 0.37 eV in an alkaline medium. The successful preparation of a large-area electrode (2 cm × 2 cm) demonstrates the scalability of this approach for fabricating molybdenum-based catalytic electrodes with enhanced HER activity in alkaline environments.