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Plasmonic waveguides have attracted tremendous interest due to efficiently confining photons on the subwavelength spatial scale to be beating the propagation diffraction limit. Transition metal molybdenum (Mo) exhibits outstanding properties in light trapping and electromagnetic field confining, making it potentially valuable in 1.55 μm plasmonic waveguide applications. However, the reliable fabrication of high-quality Mo plasmonic waveguides is a significant challenge. A real-space micro-imaging study of the surface plasmon on Mo structures is still absent. In this study, we successfully prepared a single-crystalline Mo microrod waveguide structure and fabricated subwavelength gratings on it. The diffraction gratings were designed, optimized, and etched to excite the surface plasmon polariton behaviour of Mo for the first time. The grating-optimized Mo microrod single-crystal reveals highly efficient waveguide performance around near-infrared spectroscopy, exhibiting a long propagation length of 32 μm and a low transmission loss of 0.067 dB μm−1. The results provide an alternative to advanced materials research and optical device applications of plasmonic waveguide systems.

Supercapacitors have gained increased attention in recent years due to their significant role in energy storage devices; their impact largely depends on the electrode material. The diversity of energy storage mechanisms means that various electrode materials can provide unique benefits for specific applications, highlighting the growing trend towards nanocomposite electrodes. Typically, these nanocomposite electrodes combine pseudocapacitive materials with carbon-based materials to form heterogeneous structural composites, often requiring complex multi-step preparation processes. This study introduces a straightforward approach to fabricate a non-carbon-based Mo@MoO2 nanosheet composite electrode using a one-step thermal evaporating vapor deposition (TEVD) method. This novel electrode features Mo at the core and MoO2 as the shell and demonstrates exceptional electrochemical performance. Specifically, at a current density of 1 A g−1, it achieves a storage capacity of 205.1 F g−1, maintaining virtually unchanged capacity after 10,000 charge–discharge cycles at 2 A g−1. The outstanding long-cycle stability is ascribed to the vertical two-dimensional geometry, the superior conductivity, and pseudocapacitance of the Mo@MoO2 core-shell nanosheets. These attributes significantly improve the electrode's charge storage capacity, charge transfer speed, and structural integrity during the cycling process. The development of the one-step grown Mo@MoO2 nanosheets offers a promising way for the advancement of high-performance, non-carbon-based supercapacitor nanocomposite electrodes. [ABSTRACT FROM AUTHOR]

Highly sensitive and wearable gas sensors are highly demanded on account of their widespread application in health and environmental monitoring. However, the sensing performance of conventional room‐temperature gas sensors are prone to fluctuate or even fail under changing humidity, temperature or putting into water, thus severely limiting their practical applications. Herein, a porous elastomer‐encapsulated hydrogel‐based oxygen sensor is designed with impressive room‐temperature sensing performance under various environmental conditions, including high precision (at ppm level), wide detection range (from 5 ppm to 90% O2), excellent repeatability, selectivity, long‐term stability, breathability, and waterproofing. The hydrophobic elastomer film prevents the water molecules from intruding and evaporating to a great extent, making the device resistant to humidity interference and applicable to underwater operation. Benefiting from the intrinsic stretchability of both hydrogel and elastomer films and their strong interfacial bonding, the final device can be stretched up to 100% strain. By integrating the sensor with a wireless circuit module, a wearable/portable oxygen sensing system for real‐time monitoring of health and environment is demonstrated, realizing timely and convenient assessment of respiratory rate, tissue oxygen, ambient oxygen, and dissolved oxygen. [ABSTRACT FROM AUTHOR]

High-melting point metallic micro-nano structural materials are well recognized as good conductors and electron emitters, particularly in the field of cold-cathode electron source and vacuum electron device applications. Developing their single-crystalline structures helps to further obtain large-current and high-power output performance; however, the controllable preparation of materials is always a difficult problem. In this study, we successfully realized the controllable self-assembled growth of high-quality needle-shaped molybdenum (Mo) micro-nano structures, by developing a modified thermal vapor deposition method. The Mo needle typically exhibits ultralong quasi-one dimension (up to ∼1.5 mm) and a sharp tip-end, with a perfect single-crystalline nature. Based on this structural feature, a type of Mo individual with a continuous structure is demonstrated to show an excellent conductivity of approximately 5 × 105 Ω–1 cm–1 and very large field emission current up to 93.1 μA with a corresponding current density of 1.2 × 105 A cm–2, standing out from most of the reported cold-cathode nanomaterials. This study provides a potential cold-cathode material with high conductivity and large current for vacuum electronic applications and also indicates a feasible path to achieve the preparation of high-quality single crystals of high-melting-point metals. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) lateral heterostructures have shown promising device applications. Although the diodelike responses across the 2D lateral heterostructure have been widely reported, the essential electrical properties, such as the Fermi levels and the lateral built-in potential, have been barely studied, especially with the applied gate voltage. In this work, we report the highly gate-tunable junction within monolayer MoS2–WS2 lateral heterostructures synthesized by our developed shortcut growth strategy. The quantitative determination between the gate voltage and the built-in potential has been revealed by the combined use of Kelvin probe force microscopy and I–V characteristics, in good agreement with the theoretical calculation results. A built-in potential up to 262 meV is observed at Vg = 40 V, which is three times larger than that at Vg = 0 V. A trap density mediated mechanism is proposed to explain the highly gate-tunable built-in potential. Based on the band-discontinuity mode, the energy-band diagram of the monolayer MoS2–WS2 lateral heterostructures is presented, which belongs to the 2D type II n–n heterojunction. Our findings demonstrate the strongly gate voltage-dependent and highly tunable built-in potential within the 2D type II heterojunction, which will become the novel building blocks for 2D optoelectronic, photodetection, and photovoltaic devices. [ABSTRACT FROM AUTHOR]

Supercapacitors have been extensively studied due to their advantages of fast-charging and discharging, high-power density, long-cycling life, low cost, etc. Exploring novel nanomaterial schemes for high-performance electrode materials is of great significance. Herein, a strategy to combine vertical graphene (VG) with MoO3 nanosheets to form a composite VG/MoO3 nanostructure is proposed. VGs as transition layers supply rich active sites for the growth of MoO3 nanosheets with increasing specific surface areas. The VG transition layer further improves the electric contact and adhesion of the MoO3 electrode, simultaneously stabilizing its volume and crystal structure during repeated redox reactions. Thus, the prepared VG/MoO3 nanosheets have been demonstrated to exhibit excellent electrochemical properties, such as high reversible capacitance, better cycling performance, and high-rate capability. [ABSTRACT FROM AUTHOR]