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Semiconducting Metal Oxide Photonic Crystal Plasmonic Photocatalysts
摘要： Plasmonic photocatalysis has facilitated rapid progress in enhancing photocatalytic efficiency under visible light irradiation. Poor visible-light-responsive photocatalytic materials and low photocatalytic efficiency remain major challenges. Plasmonic metal–semiconductor heterostructures where both the metal and semiconductor are photosensitive are promising for light harvesting catalysis, as both components can absorb solar light. Efficiency of photon capture can be further improved by structuring the catalyst as a photonic crystal. Here, the synthesis of photonic crystal plasmonic photocatalyst materials using Au nanoparticle-functionalized inverse opal (IO) photonic crystals is reported. A catalyst prepared using a visible-light-responsive semiconductor (V2O5) displayed over an order of magnitude increase in reaction rate under green light excitation (λ = 532 nm) compared to no illumination. The superior performance of Au-V2O5 IO is attributed to spectral overlap of the electronic bandgap, localized surface plasmon resonance, and incident light source. For the Au-TiO2 catalyst, despite coupling of the LSPR and excitation source at λ = 532 nm, this is not as effective in enhancing photocatalytic activity compared to carrying out the reaction under broadband visible light, which is attributed to improved photon adsorption in the visible by the presence of a photonic bandgap, and exploiting slow light in the photonic crystal to enhance photon absorption to create this synergistic type of photocatalyst.
关键词： photonic crystal,nitrophenol reduction,catalyst,plasmonic nanoparticles,photocatalysis
更新于2025-09-23 15:21:01
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Formation of Hierarchical FeCoS2a??CoS2 Doublea??Shelled Nanotubes with Enhanced Performance for Photocatalytic Reduction of CO2
摘要： Hierarchical FeCoS2-CoS2 double-shelled nanotubes have been rationally designed and constructed for efficient photocatalytic CO2 reduction under visible light. The synthetic strategy, engaging the two-step cation-exchange reactions, precisely integrates two metal sulfides into a double-shelled tubular heterostructure with both of the shells assembled from ultrathin two-dimensional (2D) nanosheets. Benefiting from the distinctive structure and composition, the FeCoS2-CoS2 hybrid can reduce bulk-to-surface diffusion length of photoexcited charge carriers to facilitate their separation. Furthermore, this hybrid structure can expose abundant active sites for enhancing CO2 adsorption and surface-dependent redox reactions, and harvest incident solar irradiation more efficiently by light scattering in the complex interior. As a result, these hierarchical FeCoS2-CoS2 double-shelled nanotubes exhibit superior activity and high stability for photosensitized deoxygenative CO2 reduction, affording a high CO-generating rate of 28.1 μmol h-1 (per 0.5 mg of catalyst).
关键词： metal sulfides,hollow,CO2 reduction,heterostructure,photocatalysis
更新于2025-09-23 15:21:01
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Dye-sensitized solar cell-thermoelectric hybrid generator utilizing bipolar conduction in a unified element
摘要： The dye-sensitized solar cell-thermoelectric hybrid generator (DS-TEG), which is a hybridization of a dye-sensitized solar cell (DSSC) and a thermoelectric generator (TEG) not at the structural level but in terms of material-level unification, is presented. The Pt-coated TE element provides electrons to the iodide/triiodide electrolyte to lower the redox barrier. This promotes the reduction of triiodide, resulting in a dramatic increase in the electron recombination lifetime. The available charge density, carrier diffusion coefficient and effective diffusion length were significantly increased when utilizing both types of carriers and acceleration in an iodide/triiodide reduction reaction in the unified DS-TEG.
关键词： Dye-sensitized solar cell,synergetic effect,dye-sensitized thermoelectric hybrid generator,thermoelectric element,triiodide reduction rate
更新于2025-09-23 15:21:01
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Designing Large Area Single Crystal Perovskite Solar Cells
摘要： Organic-inorganic halide single-crystal perovskite solar cells (PSCs) are promising for higher efficiency and better stability, while their development lags far behind polycrystalline counterpart. In particular, low efficiency (<5%) of large-area devices makes it challenging to be an alternative perovskite photovoltaic technology. In this perspective, we highlight the optimization of crystal growth and reduction of crystal thickness are keys to improve performance of the large-area single-crystal PSCs. After analyzing the characteristics of perovskite crystal growth methods and efficiency evolution of single-crystal PSCs, we conclude the low efficiency of large-area devices is due to conflict between low crystal quality and large crystal thickness. Then, we propose methods to grow high-quality perovskite single crystals and possible strategy to reduce the crystal thickness. Finally, investigation of key factors and exploration of large-area application are suggested to be conducted in parallel for future development of single-crystal PSCs.
关键词： large area,perovskite solar cells,single crystal,thickness reduction,crystal growth
更新于2025-09-23 15:21:01
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[IEEE 2019 International Semiconductor Conference (CAS) - Sinaia, Romania (2019.10.9-2019.10.11)] 2019 International Semiconductor Conference (CAS) - Broadband Y-type Divider in Ku-band Using Substrate Integrated Waveguide
摘要： Clipping is one of the simplest peak-to-average power ratio reduction schemes for orthogonal frequency division multiplexing (OFDM). Deliberately clipping the transmission signal degrades system performance, and clipping mitigation is required at the receiver for information restoration. In this paper, we acknowledge the sparse nature of the clipping signal and propose a low-complexity Bayesian clipping estimation scheme. The proposed scheme utilizes a priori information about the sparsity rate and noise variance for enhanced recovery. At the same time, the proposed scheme is robust against inaccurate estimates of the clipping signal statistics. The undistorted phase property of the clipped signal, as well as the clipping likelihood, is utilized for enhanced reconstruction. Furthermore, motivated by the nature of modern OFDM-based communication systems, we extend our clipping reconstruction approach to multiple antenna receivers and multi-user OFDM. We also address the problem of channel estimation from pilots contaminated by the clipping distortion. Numerical findings are presented that depict favorable results for the proposed scheme compared to the established sparse reconstruction schemes.
关键词： Clipping,Bayesian sparse signal estimation,OFDM,PAPR reduction,multi-user communication,channel estimation
更新于2025-09-23 15:21:01
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Laser and ion beams graphene oxide reduction for microelectronic devices
摘要： Reduced graphene oxide (rGO) is a two-dimensional material, which is attracting increasing attention due to its special properties. It can be obtained by laser or ion beam irradiations of pristine graphene oxide (GO). It shows high mechanical resistance, considerable electric and thermal conductivity. All these rGO characteristics together with the high number of molecular species that can be embedded between its layers, make graphene oxide a potential material for electronic sensors or efficient support on which conductive strips, condensers, and micrometric electronic devices can be designed. In particular, as it is described in this paper, it is possible to carry out high spatial resolution lithography in GO by using a focused laser or micro ion beam in order to design macro, micro, and submicron geometrical structures. The use of the reduced graphene oxide for the laser and ion beam fabrication of electrical resistances and capacitances is presented.
关键词： ion beam,lithography,ion beam reduction,electronic device,Graphene oxide,laser
更新于2025-09-23 15:21:01
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[Laser Institute of America ICALEO?? 2014: 33rd International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - San Diego, California, USA (October 19a??23, 2014)] International Congress on Applications of Lasers & Electro-Optics - Optimisation of underwater laser cutting for decommissioning purposes
摘要： In both the nuclear and offshore sectors, there are many potential applications for underwater cutting. Although underwater cutting using lasers was demonstrated many years ago, the limitations imposed at that time by the 10 micron laser beam wavelength available, meant realisation of underwater laser cutting was almost impossible. With the advent of fibre delivered laser power this situation has changed. This paper will describe recent work using a 5kW Yb fibre laser source, equipped with a specially designed process head for underwater laser cutting. Results will be presented for cutting both 304 stainless and C-Mn (S275JR) steel, at thicknesses of up to 32mm. The paper will also describe the various parameters thought to be important in underwater cutting and their effects on the cut achieved. It will be shown that for different applications, different sets of parameters can be used to achieve different results. As an example of this, in the application of nuclear decommissioning, for maximising dross height on the parts being cut will be described. In nuclear decommissioning, maximising the dross adhesion is important, as it means less radioactive material from the kerf is released into the water and therefore more remains on the parts being size reduced for future long term storage.
关键词： underwater laser cutting,decommissioning,dross height,nuclear,offshore,mass reduction,fibre laser
更新于2025-09-23 15:21:01
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Enhancing Galvanic Replacement in Plasmonic Hollow Nanoparticles: Understanding the Role of the Speciation of Metal Ion Precursors
摘要： Hollow nanostructures offer great potential for plasmonic applications due to their strong and highly tunable localized surface plasmon resonance. The relationship between the plasmonic properties and geometry of hollow nanoparticles, such as core-shell size ratio, concentricity of the cavity and porosity of the wall, is well documented. Nanoscale galvanic replacement provides a simple, versatile and powerful route for the preparation of such hollow structures. Here we demonstrate how the efficiency of reductant-assisted galvanic replacement processes can be enhanced by controlling the degree of hydration and hydrolysis of the metal ion precursor using pH and pL as key control parameters (by analogy to pH, the letter p in the expression pL is used to indicate the decimal cologarithm associated with the concentration of the ligand L). Adjusting precursor speciation prior to the sacrificial template’s hollowing process offers a new strategy to tune the morphology and optical properties of plasmonic hollow nanostructures.
关键词： co-reduction,localized surface plasmon resonance,nanoscale galvanic replacement,hollow nanoparticle synthesis,Ag-Au, Ag-Pd and Ag-Pt alloys,aqueous metal ion speciation
更新于2025-09-23 15:21:01
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Highly Selective Photoreduction of CO <sub/>2</sub> with Suppressing H <sub/>2</sub> Evolution by Plasmonic Au/CdSea??Cu <sub/>2</sub> O Hierarchical Nanostructures under Visible Light
摘要： Here, the photocatalytic CO2 reduction reaction (CO2RR) with the selectivity of carbon products up to 100% is realized by completely suppressing the H2 evolution reaction under visible light (λ > 420 nm) irradiation. To target this, plasmonic Au/CdSe dumbbell nanorods enhance light harvesting and produce a plasmon-enhanced charge-rich environment; peripheral Cu2O provides rich active sites for CO2 reduction and suppresses the hydrogen generation to improve the selectivity of carbon products. The middle CdSe serves as a bridge to transfer the photocharges. Based on synthesizing these Au/CdSe–Cu2O hierarchical nanostructures (HNSs), efficient photoinduced electron/hole (e?/h+) separation and 100% of CO selectivity can be realized. Also, the 2e?/2H+ products of CO can be further enhanced and hydrogenated to effectively complete 8e?/8H+ reduction of CO2 to methane (CH4), where a sufficient CO concentration and the proton provided by H2O reduction are indispensable. Under the optimum condition, the Au/CdSe–Cu2O HNSs display high photocatalytic activity and stability, where the stable gas generation rates are 254 and 123 μmol g?1 h?1 for CO and CH4 over a 60 h period.
关键词： photocatalytic CO2 reduction,plasmonic heterostructures,visible light,H2 evolution
更新于2025-09-23 15:21:01
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Study on void reduction in direct wafer bonding using Al <sub/>2</sub> O <sub/>3</sub> /HfO <sub/>2</sub> bonding interface for high-performance Si high- <i>k</i> MOS optical modulators
摘要： We have investigated the direct wafer bonding (DWB) method with a thin bonding dielectric interface to fabricate Si high-k MOS optical modulators with a thin equivalent oxide thickness (EOT). To suppress void generation on the bonded wafer during high-temperature annealing, we examined the high-k dielectric bonding interfacial layers, such as Al2O3 and HfO2. We found that the Al2O3/HfO2 bilayer enables void-less wafer bonding in conjunction with pre-bonding annealing at 700 °C. By using the 0.5-nm Al2O3/2.0-nm HfO2 bonding interface, the density of voids is reduced by three orders of magnitude as compared with that in the case of using the Al2O3 bonding interface. We achieved a density of voids of approximately 2 ' 10%3 cm%2 even when the bonded wafer is annealed at 700 °C. By thermal desorption spectroscopy (TDS), we found that degassing from the bonding interface is successfully suppressed by the introduction of the HfO2 layer and the pre-bonding annealing at 700 °C, which are considered to suppress void generation. Wafer bonding with thin Al2O3/HfO2 high-k bonding interface is promising for Si high-k MOS optical modulators.
关键词： Al2O3,void reduction,MOS optical modulators,high-k dielectric,HfO2,direct wafer bonding
更新于2025-09-23 15:21:01