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Influence of Semiconductor Morphology on Photocatalytic Activity of Plasmonic Photocatalysts: Titanate Nanowires and Octahedral Anatase Nanoparticles
摘要： Octahedral anatase particles (OAP) with eight exposed and thermodynamically most stable (101) facets were prepared by an ultrasonication-hydrothermal (US-HT) reaction from potassium titanate nanowires (TNW). The precursor (TNW) and the product (OAP) of US-HT reaction were modi?ed with nanoparticles of noble metals (Au, Ag or Pt) by photodeposition. Samples were characterized by X-ray di?raction (XRD), X-ray photoelectron spectroscopy (XPS), di?use re?ectance spectroscopy (DRS), scanning transmission electron microscopy (STEM) and time-resolved microwave conductivity (TRMC). The photocatalytic activity was investigated in three reaction systems, i.e., anaerobic dehydrogenation of methanol and oxidative decomposition of acetic acid under UV/vis irradiation, and oxidation of 2-propanol under vis irradiation. It was found that hydrogen liberation correlated with work function of metals, and thus the most active were platinum-modi?ed samples. Photocatalytic activities of bare and modi?ed OAP samples were much higher than those of TNW samples, probably due to anatase presence, higher crystallinity and electron mobility in faceted NPs. Interestingly, noble metals showed di?erent in?uence on the activity depending on the semiconductor support, i.e., gold-modi?ed TNW and platinum-modi?ed OAP exhibited the highest activity for acetic acid decomposition, whereas silver- and gold-modi?ed samples were the most active under vis irradiation, respectively. It is proposed that the form of noble metal (metallic vs. oxidized) as well as the morphology (well-organized vs. uncontrolled) have a critical e?ect on the overall photocatalytic performance. TRMC analysis con?rmed that fast electron transfer to noble metal is a key factor for UV activity. It is proposed that the e?ciency of plasmonic photocatalysis (under vis irradiation) depends on the oxidation form of metal (zero-valent preferable), photoabsorption properties (broad localized surface plasmon resonance (LSPR)), kind of metal (silver) and counteraction of “hot” electrons back transfer to noble metal NPs (by controlled morphology and high crystallinity).
关键词： silver,platinum,gold,photocatalyst morphology,faceted titania,morphology-governed activity,plasmonic photocatalysis,octahedral particle,titanate nanowire,noble metal
更新于2025-09-11 14:15:04
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Optimization of light trapping in square and hexagonal grid inclined silicon nanowire solar cells
摘要： In this paper, we focus on the optimization of four inclined nanowire solar cell designs by calculating optimum nanowire dimensions and the inclination angle using the particle swarm optimization (PSO) algorithm. Two types of the nanowire arrangements in an array (grid) has been investigated and hexagonal grid has been proposed as an efficient arrangement pattern for nanowire solar cells with superior light trapping and absorption properties. The effect of the nanowire cross sections on the performance of the solar cell in each grid has been studied and it has been proved that the nanowires with circular cross sections in a hexagonal grid provide the best characteristics. For the first time, four design parameters of a nanowire solar cell including the nanowire dimensions and the inclination angle have been optimized simulatnously by using PSO algorithm. The absorption efficiencies above 40 % and the current densities above 50 mA/cm2 have been achieved in optimum cases. The absorption, electric field, absorption efficiency and the current density have been calculated for all the structures and have been compared to each other. The results show that all the proposed solar cell designs, after optimization, outperform the previous works.
关键词： Optimization,Absorption,Inclined Nanowire,Current Density,Solar Cell
更新于2025-09-11 14:15:04
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Low-cost photodetector architectures fabricated at room-temperature using nano-engineered silicon wafer and sol-gel TiO2 – based heterostructures
摘要： In the last decades, significant research has been done on the nanocrystalline forms of titanium dioxide (tio2). Amorphous TiO2 has not been studied intensively despite being significantly less expensive compared to crystalline TiO2. This study reveals significant improvement in UV-VIS photodetection properties from heterostructures fabricated in ambient environment using n-type silicon nanowire arrays and amorphous TiO2 sol-gel. Our ultra-low-cost UV-VIS photodetectors can cover a wide range of applications. We report fast rise/decay time constants of 0.23 ms/0.17 ms and high responsivity up-to 6.0 A/W in the UV and 25.0 A/W in the visible range under low (1 V) external bias. The large surface area due to the nanowire array architecture leads to 2 orders of magnitude enhancement in photo-response. Besides the final electrode deposition, the entire device fabrication is performed using low-cost, all solution-based methods in ambient conditions. These low-cost UV-Visible broadband photodetectors can potentially serve a wide range of applications.
关键词： heterostructures,UV-VIS photodetection,TiO2,silicon nanowire,photodetector
更新于2025-09-11 14:15:04
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Nanowire network-based photodetectors with imaging performance for omnidirectional photodetecting through a wire-shaped structure
摘要： Wearable photodetectors (PDs) have attracted extensive attention from both scientific and industrial areas due to intrinsic detection abilities as well as promising applications in flexible, intelligent, and portable fields. However, most of the existing PDs have rigid planar or bulky structures which cannot fully meet the demands of these unique occasions. Here, we present a highly flexible, omnidirectional PD based on ZnO nanowire (NW) networks. ZnO NW network-based PDs exhibit the imageable level performance with an on/off ratio of about 104. Importantly, a ZnO NW network can be assembled onto wire-shaped substrates to construct omnidirectional PDs. As a result, the wire-shaped PDs have excellent flexibility, a large light on/off ratio larger than 103, and 360° no blind angle detecting. Besides, they exhibit extraordinary stability against bending and irradiation. These results demonstrate a novel strategy for building wire-shaped optoelectronic devices through a NW network structure, which is highly promising for future smart and wearable applications.
关键词： Wearable photodetectors,Flexible optoelectronic devices,Omnidirectional photodetecting,ZnO nanowire networks
更新于2025-09-11 14:15:04
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A 3D hybrid nanowire/microcuboid optoelectronic electrode for maximised light harvesting in perovskite solar cells
摘要： A high-performance optoelectronic device requires efficient light harvesting and management in the electrodes. In this work, we report the integration of antireflective anatase TiO2 nanowire (TNW) arrays and CH3NH3PbI3 microcuboid (CMC) film into a new bilayer architecture. The highly porous and well-interconnected anatase TNW arrays showcase antireflective properties for enhanced light transmittance and provide a largely accessible surface area for anchoring the perovskite light absorber. The thick and compact CMC film enables efficient light absorption. Thus, perovskite solar cells (PSCs) fabricated with a hybrid TNW/CMC optoelectronic electrode achieved an optimal power conversion efficiency (PCE) of up to 20.1% under one sun illumination with a high Jsc of 23.2 mA cm?2, which can be attributed to the maximised light harvesting efficiency within the devices.
关键词： light harvesting,perovskite solar cells,CH3NH3PbI3 microcuboid,optoelectronic electrode,TiO2 nanowire
更新于2025-09-11 14:15:04
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Superior properties in room-temperature colloidal-dot quantum emitters revealed by ultralow-dark-count detections of temporally-purified single photons
摘要： The realization of high-quality quantum emitters that can operate at room temperature is important for accelerating the application of quantum technologies, such as quantum communication, quantum information processing, and quantum metrology. In this work, we study the photon-antibunching properties on room-temperature emission from individual colloidal quantum dots (CQDs) using superconducting-nanowire single-photon detectors and temporal filtering of the photoluminescence decay curve. We find that high single-photon purities and high photon-generation rates can be simultaneously achieved by removing the signals originating from the sequential two-photon emission of biexcitons created by multiple excitation pulses. We successfully demonstrate that the ultrahigh performance of the room-temperature single-photon sources showing g(2)(0) ? 10?2 can be confirmed by the ultralow-dark-count detection of the temporally purified single photons. These findings provide strong evidence for the attractiveness of CQDs as candidates for high-quality room-temperature quantum light sources.
关键词： single-photon sources,room-temperature,superconducting-nanowire single-photon detectors,quantum emitters,colloidal quantum dots,temporal filtering
更新于2025-09-11 14:15:04
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A Silicon Shallow-Ridge Waveguide Integrated Superconducting Nanowire Single Photon Detector Towards Quantum Photonic Circuits
摘要： A silicon shallow-ridge waveguide integrated superconducting nanowire single photon detector is designed and fabricated. At the bias current of 11.6 ??A, 4% on-chip detection efficiency near 1550 nm wavelength is achieved with the dark count rate of 3 Hz and a timing jitter of 75 ps. This device shows the potential application in the integration of superconducting nanowire single photon detectors with a complex quantum photonic circuit.
关键词： quantum photonic circuits,silicon shallow-ridge waveguide,superconducting nanowire single photon detector
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Crystal Growth and Optical Property of GaN Nanowire Cores and GaInN/GaN Multi-Quantum Shells Grown by Metalorganic Vapor Phase Epitaxy
摘要： An n-GaN nanowire and a GaInN/GaN multi-quantum shell (MQS) were uniformly grown by the continuous flow mode MOVPE with the optimal growth condition. Although the extended defect-free crystal was successfully grown, the MQS may contain point defects acting as the nonradiative recombination centers. The AlGaN underlying shell was found to be effective point defect trap to improve the optical property of the MQS.
关键词： AlGaN,optical property,point defect,multi-quantum shell,nanowire
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || Quantitative measurement of doping and surface charge in a ZnO nanowire using in-situ biasing and off-axis electron holography
摘要： The measurement of doping and surface charge in a Zn2N3 nanowire using in-situ biasing and off-axis electron holography
关键词： surface charge,in-situ biasing,off-axis electron holography,Zn2N3 nanowire,doping
更新于2025-09-11 14:15:04
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Optically oriented attachment of nanoscale metal-semiconductor heterostructures in organic solvents via photonic nanosoldering
摘要： As devices approach the single-nanoparticle scale, the rational assembly of nanomaterial heterojunctions remains a persistent challenge. While optical traps can manipulate objects in three dimensions, to date, nanoscale materials have been trapped primarily in aqueous solvents or vacuum. Here, we demonstrate the use of optical traps to manipulate, align, and assemble metal-seeded nanowire building blocks in a range of organic solvents. Anisotropic radiation pressure generates an optical torque that orients each nanowire, and subsequent trapping of aligned nanowires enables deterministic fabrication of arbitrarily long heterostructures of periodically repeating bismuth-nanocrystal/germanium-nanowire junctions. Heat transport calculations, back-focal-plane interferometry, and optical images reveal that the bismuth nanocrystal melts during trapping, facilitating tip-to-tail “nanosoldering” of the germanium nanowires. These bismuth-semiconductor interfaces may be useful for quantum computing or thermoelectric applications. In addition, the ability to trap nanostructures in oxygen- and water-free organic media broadly expands the library of materials available for optical manipulation and single-particle spectroscopy.
关键词： bismuth-nanocrystal/germanium-nanowire junctions,organic solvents,optical traps,photonic nanosoldering,nanoscale metal-semiconductor heterostructures
更新于2025-09-11 14:15:04