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Nanophotonic devices, composed of metals, dielectrics, or semiconductors, enable precise and high-spatial-resolution manipulation of electromagnetic waves by leveraging diverse light–matter interaction mechanisms at subwavelength length scales. Their compact size, light weight, versatile functionality and unprecedented performance are rapidly revolutionizing how optical devices and systems are constructed across the infrared, visible, and ultraviolet spectra. Here, we review recent advances and future opportunities of nanophotonic elements operating in the ultraviolet spectral region, which include plasmonic devices, optical metamaterials, and optical metasurfaces. We discuss their working principles, material platforms, fabrication, and characterization techniques, followed by representative device applications across various interdisciplinary areas such as imaging, sensing and spectroscopy. We conclude this review by elaborating on future opportunities and challenges for ultraviolet nanophotonic devices.

Dielectric metasurfaces, composed of planar arrays of subwavelength dielectric structures that collectively mimic the operation of conventional bulk optical elements, have revolutionized the field of optics by their potential in constructing high-efficiency and multi-functional optoelectronic systems on chip. The performance of a dielectric metasurface is largely determined by its constituent material, which is highly desired to have a high refractive index, low optical loss and wide bandgap, and at the same time, be fabrication friendly. Here, we present a new material platform based on tantalum pentoxide (Ta2O5) for implementing high-performance dielectric metasurface optics over the ultraviolet and visible spectral region. This wide-bandgap dielectric, exhibiting a high refractive index exceeding 2.1 and negligible extinction coefficient across a broad spectrum, can be easily deposited over large areas with good quality using straightforward physical vapor deposition, and patterned into high-aspect-ratio subwavelength nanostructures through commonly-available fluorine-gas-based reactive ion etching. We implement a series of high-efficiency ultraviolet and visible metasurfaces with representative light-field modulation functionalities including polarization-independent high-numerical-aperture lensing, spin-selective hologram projection, and vivid structural color generation, and the devices exhibit operational efficiencies up to 80%. Our work overcomes limitations faced by scalability of commonly-employed metasurface dielectrics and their operation into the visible and ultraviolet spectral range, and provides a novel route towards realization of high-performance, robust and foundry-manufacturable metasurface optics.

Structural colors, resulting from the interaction of light with nanostructured materials rather than pigments, present a promising avenue for diverse applications ranging from ink-free printing to optical anti-counterfeiting. Achieving structural colors with high purity and brightness over large areas and at low costs is beneficial for many practical applications, but still remains a challenge for current designs. Here, we introduce a novel approach to realizing large-scale structural colors in layered thin film structures that are characterized by both high brightness and purity. Unlike conventional designs relying on single Fabry–Pérot cavity resonance, our method leverages coupled resonance between adjacent cavities to achieve sharp and intense transmission peaks with significantly suppressed sideband intensity. We demonstrate this approach by designing and experimentally validating transmission-type red, green, and blue colors using an Ag/SiO /Ag/SiO /Ag configuration on fused silica substrate. The measured spectra exhibit narrow resonant linewidths (full width at half maximum ∼60 nm), high peak efficiencies (>40 %), and well-suppressed sideband intensities (∼0 %). In addition, the generated color can be easily tuned by adjusting the thickness of SiO layer, and the associated color gamut coverage shows a wider range than many existing standards. Moreover, the proposed design method is versatile and compatible with various choices of dielectric and metallic layers. For instance, we demonstrate the production of angle-robust structural colors by utilizing high-index Ta as the dielectric layer. Finally, we showcase a series of printed color images based on the proposed structures. The coupled-cavity-resonance architecture presented here successfully mitigates the trade-off between color brightness and purity in conventional layered thin film structures and provides a novel and cost-effective route towards the realization of large-scale and high-performance structural colors.

Iron-based catalysts are promising candidates for advanced oxidation process-based wastewater remediation. However, the preparation of these materials often involves complex and energy intensive syntheses. Further, due to the inherent limitations of the preparation conditions, it is challenging to realise the full potential of the catalyst. Herein, we develop an iron-based nanomaterial catalyst via soft carbon assisted flash joule heating (FJH). FJH involves rapid temperature increase, electric shock, and cooling, the process simultaneously transforms a low-grade iron mineral (FeS) and soft carbon into an electron rich nano Fe 0 /FeS heterostructure embedded in thin-bedded graphene. The process is energy efficient and consumes 34 times less energy than conventional pyrolysis. Density functional theory calculations indicate that the electron delocalization of the FJH-derived heterostructure improves its binding ability with peroxydisulfate via bidentate binuclear model, thereby enhancing ·OH yield for organics mineralization. The Fe-based nanomaterial catalyst exhibits strong catalytic performance over a wide pH range. Similar catalysts can be prepared using other commonly available iron precursors. Finally, we also present a strategy for continuous and automated production of the iron-based nanomaterial catalysts. There is an urgent need to develop efficient Fe-based catalysts for the organic pollutant degradation. Here, the authors develop an iron-based nanomaterial catalyst via flash joule heating. This catalyst exhibits strong energy efficient catalytic performance over a wide pH range and is potentially scalable.

Flash Joule heating (FJH) is an emerging and profitable technology for converting inexhaustible biomass into flash graphene (FG). However, it is challenging to produce biomass FG continuously due to the lack of an integrated device. Furthermore, the high-carbon footprint induced by both excessive energy allocation for massive pyrolytic volatiles release and carbon black utilization in alternating current-FJH (AC-FJH) reaction exacerbates this challenge. Here, we create an integrated automatic system with energy requirement-oriented allocation to achieve continuous biomass FG production with a much lower carbon footprint. The programmable logic controller flexibly coordinated the FJH modular components to realize the turnover of biomass FG production. Furthermore, we propose pyrolysis-FJH nexus to achieve biomass FG production. Initially, we utilize pyrolysis to release biomass pyrolytic volatiles, and subsequently carry out the FJH reaction to focus on optimizing the FG structure. Importantly, biochar with appropriate resistance is self-sufficient to initiate the FJH reaction. Accordingly, the medium-temperature biochar-based FG production without carbon black utilization exhibited low carbon emission (1.9 g CO 2 -eq g −1 graphene), equivalent to a reduction of up to ~86.1% compared to biomass-based FG production. Undoubtedly, this integrated automatic system assisted by pyrolysis-FJH nexus can facilitate biomass FG into a broad spectrum of applications. It is challenging to produce biomass FG continuously due to the lack of an integrated device. Here, we create an integrated automatic system with energy requirement-oriented allocation to achieve continuous biomass FG production with a much lower carbon footprint.

Triboelectric nanogenerators (TENGs) have emerged as a promising approach for generating electricity and providing electrical stimuli in medical electronic devices. Despite their potential benefits, the clinical implementation of TENGs faces challenges such as skin compliance and a lack of comprehensive assessment regarding their biosafety and efficacy. Therefore, further research is imperative to overcome these limitations and unlock the full potential of TENGs in various biomedical applications. In this study, we present a flexible silk fibroin-based triboelectric nanogenerator (SFB-TENG) that features an on-skin substrate and is characterized by excellent skin compliance and air/water permeability. The range of electrical output generated by the SFB-TENG was shown to facilitate the migration and proliferation of Hy926, NIH-3T3 and RSC96 cells. However, apoptosis of fibroblast NIH-3T3 cells was observed when the output voltage increased to more than 20 V at a frequency of 2 Hz. In addition, the moderate electrical stimulation provided by the SFB-TENG promoted the cell proliferation cycle in Hy926 cells. This research highlights the efficacy of a TENG system featuring a flexible and skin-friendly design, as well as its safe operating conditions for use in biomedical applications. These findings position TENGs as highly promising candidates for practical applications in the field of tissue regeneration.

In this paper, metal sulfide materials have been explored for the first time as a new choice of bifunctional cathode electrocatalyst materials for non-aqueous lithium-air batteries (LABs). Nickel sulfides with two different morphologies of flower-like (f-NiS) and rod-like (r-NiS) are successfully synthesized using a hydrothermal method with and without the assistance of cetyltrimethyl ammonium bromide. As LAB cathode catalysts, both f-NiS and r-NiS demonstrate excellent catalytic activities towards the formation and decomposition of Li2O2, resulting in improved specific capacity, reduced overpotentials and enhanced cycling performance when compared to those of pure Super P based electrode. Moreover, the morphology of NiS materials can greatly affect LAB performance. Particularly, the f-NiS is more favorable than r-NiS in terms of their application in LABs. When compared to both r-NiS and pure super P materials as LAB cathode materials, this f-NiS catalyst material can give the highest capacity of 6733 mA h g−1 and the lowest charge voltage of 4.24 V at the current density of 75 mA g−1 and also exhibit an quite stable cycling performance.

The difference of the mechanical performance between the whole bridge pylon and the segment model are analyzed in theoretical method to provide theoretical support for the full-scale segmental model test study. Firstly, choose the most representative full-scale segment in anchorage zone of bridge pylon. Secondly, select the whole model composed of several segments. Finally, analysis the stress distributions in two models under the working load and the cracking load. In the coordinate segment position, stress distribution under design cable force in whole model and full scale segment model is almost the same. It indicates that the working performance of the anchorage zone in the bridge pylon can be studied through the full-scale segment model test.

针对现阶段微观剩余油研究中可视化精度低、微观剩余油与矿物之间的依存关系不明确以及形态分类描述不完善等问题,利用岩芯观察、铸体薄片分析、X射线衍射分析等手段,以场发射环境扫描电子显微镜(FE-SEM)图像为基础资料,联合能谱(EDS)分析资料,研究鄂尔多斯盆地中部长2油层组和长9油层组的微观剩余油分布规律,并探讨剩余油赋存状态的矿物学机制.结果表明,微观剩余油的赋存状态由孔隙的大小和形态以及与孔隙相接触的边缘矿物的性质共同决定,不同类型孔隙对剩余油的赋存能力取决于孔隙边缘矿物的形态、表面粗糙程度、比重和润湿性等物理化学性质.据此,可将微观剩余油分为残留油团、半自由油岛、半自由油雾、半自由微油团和束缚油5个类型.