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Facile strategy for controllable synthesis of hierarchical hollow MoS2 microspheres with enhanced photocatalytic properties
摘要： Tailored design of photocatalysts with complicated hollow structures is of great importance for promoting environmental remediation. In this paper, monodispersed hierarchical hollow MoS2 microspheres have been prepared via a facile and economical hydrothermal method with the assistance of surfactant (polyethylene-polypropylene glycol (F68)). The unusual design displays three important features: large specific surface area, strong light absorption, and rich catalytic active sites. The specific surface area of the hierarchical hollow MoS2 microspheres is 21.75 m2g-1, which is higher than that of MoS2 particles (4.05 m2g-1) and commercial MoS2 (2.84 m2g-1). Meanwhile, the hierarchical hollow MoS2 microspheres possess strong light absorption around a broadband wavelength from 200 nm to 800 nm. Furthermore, the ordered MoS2 nanosheets which assemble to the outer surface of the hierarchical hollow MoS2 microspheres display rich catalytic active sites, which are beneficial in promoting the fast transport of charge carriers during the process of photocatalytic reaction. As a result, the photodegradation activity test demonstrates that the hierarchical hollow MoS2 microspheres exhibit excellent photocatalytic activity and recycling stability. The reaction rate constant of the hierarchical hollow MoS2 microspheres for the photodegradation of RhB is 25.32 and 18.18 times faster than that of MoS2 particles and commercial MoS2, respectively.
关键词： Unusual design,Photocatalysts,MoS2,Rich catalytic sites,Large surface area,Broadband absorption
更新于2025-09-23 15:23:52
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Black Diatom Colloids toward Efficient Photothermal Converters for Solar-to-Steam Generation
摘要： Steam generation from solar power using converters has attracted significant research attention in recent years as an alternative form of energy conversion from solar energy. Rationally designed photothermal converters are essential to increase the efficiency of steam generation. Here we propose a novel colloidal type of photothermal converter based on a frustule skeleton, which is a naturally designed colloid containing through-pore structures. Several coating processes were used to provide broadband absorption, magnetic, and water-floating properties without deteriorating pore structures, through vapor deposition polymerization of polypyrrole, weak base treatment, and additional vapor deposition polymerization of polystyrene. The prepared colloidal photothermal converter showed superior efficiency for steam generation under sun-light irradiation.
关键词： Solar-to-steam generation,surface treatment,diatom,chemical vapor deposition,broadband absorption
更新于2025-09-23 15:23:52
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Manipulating disordered plasmonic systems by external cavity with transition from broadband absorption to reconfigurable reflection
摘要： Disordered biostructures are ubiquitous in nature, usually generating white or black colours due to their broadband optical response and robustness to perturbations. Through judicious design, disordered nanostructures have been realised in artificial systems, with unique properties for light localisation, photon transportation and energy harvesting. On the other hand, the tunability of disordered systems with a broadband response has been scarcely explored. Here, we achieve the controlled manipulation of disordered plasmonic systems, realising the transition from broadband absorption to tunable reflection through deterministic control of the coupling to an external cavity. Starting from a generalised model, we realise disordered systems composed of plasmonic nanoclusters that either operate as a broadband absorber or with a reconfigurable reflection band throughout the visible. Not limited to its significance for the further understanding of the physics of disorder, our disordered plasmonic system provides a novel platform for various practical application such as structural colour patterning.
关键词： broadband absorption,external cavity,disordered plasmonic systems,tunable reflection,structural colour patterning
更新于2025-09-23 15:21:01
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Approaching the Yablonovitch limit with free-floating arrays of subwavelength trumpet non-imaging light concentrators driven by extraordinary low transmission
摘要： Metamaterials based on arrays of subwavelength dielectric structures has recently proved a viable research venue towards the realization of various photonic devices. In the current study we introduce a new approach towards efficient light trapping and the broadband absorption of the solar radiation based on silicon surface arrays composed of subwavelength trumpet non-imaging light concentrators (henceforth, trumpet arrays). In geometrical optics, a three-dimensional trumpet non-imaging light concentrator is a hyperboloid of revolution with an ideal light concentration ratio. We use finite-difference time-domain electromagnetic calculations to examine the optical response of an infinite cubic-tiled substrate-less silicon trumpet array under normal illumination. The absorptivity spectra of trumpet arrays are characterized by strong absorption peaks, some of which are just below the Yablonovitch limit. The enhanced light trapping is attributed solely to efficient occupation of the array Mie modes, and we show absorption enhancement at the near infrared that is an order of magnitude higher than that of optimized nanopillar (NP) arrays. We show superior broadband absorption of the solar radiation in trumpet arrays (with unoptimized geometry) compared with that of optimized NP arrays (~26% enhancement). The higher optical absorption in trumpet array is governed by low transmissivity, in contrast with NP array in which the absorption is governed by low reflectivity. Finally, we show that low reflectivity in trumpet arrays is governed by modal excitations at the upper part of the trumpets (which is also supported by the weak dependency of the reflectivity on the array height), whereas the transmissivity is governed by modal excitations at the lower part of the trumpets.
关键词： non-imaging light concentrators,Mie modes,nano-photonics,broadband absorption of solar radiation,light trapping
更新于2025-09-19 17:15:36
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Broadband perfect absorption enabled by using terahertz metamaterial resonator
摘要： Broadband metamaterial perfect absorbers are of paramount importance in many applications. However, these broadband absorbers are typically based on complex structure designs, the manufacturing process of them is highly challenging. This paper shows that a fairly simple structure formed by a rectangular metallic patch with two rectangular holes backed by two layers of dielectric sheet and metallic mirror is utilized to obtain the broadband absorption. The structure possesses three different but similar resonance peaks, and the superposition of them can realize a bandwidth of 1.00 THz with absorption >80%. The absorber physical origin is elucidated by means of the corresponding field distributions of the three absorption modes. Furthermore, the device bandwidth can be tuned via changing the sizes of the resonator. These absorption properties using the simple structure design can benefit a wide range of applications.
关键词： Metamaterials,Broadband absorption,Terahertz
更新于2025-09-19 17:13:59
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Theoretical investigation of broadband absorption enhancement in a-Si thin-film solar cell with nanoparticles
摘要： Thin-film solar cells have attracted increasing attention due to its low material cost and large flexibility, but they also face the challenge of low solar absorption due to reduced active layer thickness. Through exciting surface plasmon resonance, plasmonic metal nanoparticles are usually placed on the cell front surface to enhance solar absorption. However, if eliminating the unuseful intrinsic absorption in nanoparticles, we find that dielectric ones are better choices to enhance a-Si thin-film solar cell absorption efficiency. Moreover, a composite light trapping structure with dielectric nanoparticles on the front surface and metal hemispheres on the rear surface is proposed to achieve broadband absorption enhancement in both short and long wavelengths, with the aim to get a higher conversion efficiency. The finite-difference-time-domain simulation results show that, compared with bare 100-nm-thick amorphous silicon solar cell, the short-circuit current density and photoelectric conversion efficiency could be respectively improved by 21% and 18% with addition of optimized composite light trapping structure. The general method proposed in this study could provide valuable guidance to light trapping structure design for various kinds of thin-film solar cells.
关键词： Broadband absorption enhancement,Thin-film solar cell,Light trapping,Conversion efficiency,Amorphous silicon,Nanoparticle
更新于2025-09-19 17:13:59
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Broadband terahertz metamaterial absorber enabled by using high-loss dielectric materials
摘要： Metamaterial absorbers consisted of two metallic layers separated by low-loss dielectric materials have been extensively presented and studied. However, these absorbers using low-loss dielectric materials usually exhibit narrow bandwidth, which are not conductive to the practical applications. Here, we demonstrate a novel terahertz meta-device that can obviously widen the absorption bandwidth of metamaterial absorber. This meta-device is composed of a high-loss dielectric material sandwiched by a metallic strip and an opaque metallic mirror. Absorption of greater than 80% of the meta-device can cover a continuous frequency range of 2.43 THz, and its relative absorption bandwidth can reach 89.17%. These two indexes are both much larger than those of previous absorption devices using low-loss dielectric materials. Physical mechanism of the meta-device originates from the superposition of two different resonant modes. More importantly, the variation of meta-device parameters can provide considerable degree of freedom to regulate the absorption bandwidth and relative absorption bandwidth of the device.
关键词： broadband absorption,metamaterials,perfect absorber,high-loss dielectric material
更新于2025-09-19 17:13:59
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[IEEE 2019 International Conference on Electrical, Communication, and Computer Engineering (ICECCE) - Swat, Pakistan (2019.7.24-2019.7.25)] 2019 International Conference on Electrical, Communication, and Computer Engineering (ICECCE) - Nanoplasmonic Quasi Crystal Metascreen Optimized for Efficient Light Absorption
摘要： A metascreen absorber composed of plasmonic nanodisk array is used to absorb incident radiation at optical frequencies. The conventional Nobel metals such as gold and silver are considered as best plasmonic materials to couple incident light to surface plasmons modes. However, it is found that alternative plasmonic materials such as copper (Cu) offers optimized absorption characteristics. Copper nanodisk absorber offers a broad range of optical absorption ranging from 400 nm – 1500 nm wavelength. In addition, it is found that the light absorption bandwidth can be signi?cantly enhanced or near perfect absorption can be reached if plasmonic nanodisks are arranged in quasi-crystal con?guration. The proposed quasicrystal based metascreen absorber offers potential applications for light energy harvesting and optical sensing applications.
关键词： Salisbury screen absorber,polarization independent,metasurface,terahertz frequencies,broadband absorption
更新于2025-09-16 10:30:52
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Broadband Solar Energy Absorption in Plasmonic Thin-Film Amorphous Silicon Solar Cell
摘要： Improving the light absorption in thin-?lm solar cell is essential for enhancing e?ciency and reducing cost. Here, we propose an ultra-broadband amorphous silicon solar cell based on a periodic array of titanium ring-shaped metasurfaces, which achieves more than 90% absorptance in the visible range of the solar spectrum. The surface plasmon resonance supported by the nanoparticles together with the resonance induced by the metal–insulator–metal Fabry–Perot cavity leads to this broadband absorption. The impact of various materials of functional layers and the geometric structure of the nanoparticle on absorption performance is discussed in detail, and super broadband resonance is achieved after optimization. Moreover, the optimized solar cell is tested for di?erent solar incidence angles and it is found that the structure exhibits high absorption e?ciency even at large angles. Thus, the proposed solar cell design may be bene?cial for most of the photovoltaic applications.
关键词： nanoparticle,antire?ection coating,solar incidence angle,broadband absorption
更新于2025-09-16 10:30:52
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All-Dielectric Terahertz Plasmonic Metamaterial Absorbers and High-Sensitivity Sensing
摘要： Two types of plasmonic metamaterial absorbers (PMAs) formed from patterned all-dielectric resonators are designed and demonstrated experimentally in the terahertz (THz) range. Both PMAs use a simple grating design on highly N-doped silicon. The first shows broadband absorption with near-perfect peak absorbance at 1.45 THz and a bandwidth of 1.05 THz for 90% absorbance, while the second is a dual-band absorber. Experiments show that the second absorber has two distinct absorption peaks at 0.96 and 1.92 THz with absorption rates of 99.7 and 99.9%, respectively. A fundamental cavity mode coupled to coaxial surface plasmon polaritons is responsible for the characteristics of both PMAs. Additionally, the optically tunable responses of these all-dielectric absorbers demonstrate that the absorption behavior can be modified. The quality factor (Q) values of the dual-band resonances are 4.6 and 7.8 times larger than those of the broadband PMAs, respectively, which leads to a better sensing performance. As an example, the two proposed PMAs act as high-sensitivity sensors and demonstrate considerable potential for chlorpyrifos detection. These results show that these PMAs can be used as sensors that can detect the presence of trace pesticides in adsorption analyses, among other practical applications.
关键词： broadband absorption,all-dielectric resonators,plasmonic metamaterial absorbers,chlorpyrifos detection,dual-band absorber,terahertz,high-sensitivity sensors
更新于2025-09-12 10:27:22