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- 2019
- solar cell
- thin film
- sputtering
- Tungsten di sulfide (WS2)
- Optoelectronic Information Materials and Devices
- Universiti Kebangsaan Malaysia
- German Malaysian Institute
- Universiti Tenaga Nasional
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1D tungsten oxide nanostructures on a Cu(1?1?0) surface
摘要： Thin epitaxial layers of tungsten oxide on metal substrates are suitable as model systems for investigation of chemical reactivity and catalytic properties. However, the ability to prepare epitaxial tungsten oxide model system in situ is quite rare. Here we present a method to prepare highly ordered tungsten oxide thin film on a Cu(1 1 0) single crystal substrate using physical vapor deposition in a reactive atmosphere of atomic oxygen. The oxygen induced reconstruction of the copper substrate gives rise to unique self-organized 1D structures of tungsten oxide parallel with the Cu[1 ?1 0] crystallographic direction. Utilizing a combination of photoemission spectroscopy and density functional theory calculations we reveal emergent physicochemical properties related to the low-dimensionality of the system. Specifically, we observe a support mediated charge redistribution at the interface and a momentum dependent modulation of the valence-band electronic structure. The unusual character of the 1D oxide nanostructures on Cu(1 1 0) surface opens up a unique avenue for preparation of tungsten oxide-based functionalized nanostructures and provides options for further investigation of the fundamental properties of tungsten oxide.
关键词： 1D structures,model system,tungsten oxide
更新于2025-09-23 15:21:01
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Photodecomposition Profile of Curcumin in the Existence of Tungsten Trioxide Particles
摘要： The purpose of this study was to investigate the stability of curcumin solution in the existence of tungsten trioxide (WO3) particles under light illumination. In the experimental method, curcumin extracted from Indonesian turmeric was added with WO3 microparticles and put into the photoreactor system. The photostability performance of curcumin was conducted for 22 hours using 100 W of Neon Lamp. The results showed that the curcumin solution was relatively stable. When curcumin without existence of WO3 was irradiated, no change in the curcumin concentration was found. However, when curcumin solution was mixed with WO3 particles, decreases in the concentration of curcumin was found. The concentration of curcumin with WO3 after light irradiation was about 73.58%. Based on the results, we concluded that the curcumin is relatively stable against light. However, its light-irradiation stability decreases with additional inorganic material.
关键词： curcumin,photodecomposition,tungsten trioxide,stability,light irradiation
更新于2025-09-23 15:21:01
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Synthesis of Tungsten Disulfide and Molybdenum Disulfide Quantum Dots and their Applications
摘要： With fascinating optical, electronic, and mechanical properties, tungsten disulfide (WS2) and molybdenum disulfide (MoS2) quantum dots (QDs) are promising for related applications. Their bandgap energy, photoluminescence and electrochemical properties are closely related to their size, morphology, dimensionality, crystal phase and structure. In this review, we introduce the crystal phases and structures of WS2 and MoS2 QDs followed by a summary of their physical and chemical synthetic methods and their applications in light-emitting devices (LEDs), supercapacitors and others. Additionally, the advantages and limitations of different synthetic strategies and challenges in these promising fields are discussed on the basis of current development.
关键词： Synthesis methods,Applications,Quantum dots,Molybdenum disulfide,Tungsten disulfide
更新于2025-09-23 15:21:01
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Perovskite Materials - Synthesis, Characterisation, Properties, and Applications || Microwave Dielectrics with Perovskite-Type Structure
摘要： Most electroceramics are ferroelectrics, but microwave dielectrics are mostly paraelectrics with a center of symmetry i. Microwave dielectrics should possess a perfect crystal structure with neither defects nor internal strain in order to be microwave friendly. They have been used in resonators and filters in mobile telecommunications devices. Perovskite and related compounds are also mostly ferroelectrics, but paraelectrics with a perovskite structure also exist, and are used in microwave dielectrics. Owing to the flexibility of the perovskite structure, many kinds of microwave dielectrics with a perovskite structure have been designed for microwave dielectrics. In this chapter, simple and complex perovskite, and perovskite related materials such as pseudo-tungsten-bronze solid solutions and homologous compounds are introduced for microwave dielectrics. The microwave dielectric properties are revealed through the crystalline structure of the material. Therefore, the relationship between the crystalline structure and properties of the material is presented, and is expected to be of use in the design of novel dielectrics. As many superior materials for microwave dielectrics have been developed and are expected to be used in new applications such as wireless sensors and wireless power transfer by resonant coupling, wave absorption by interference and transparent ceramics with no birefringence, these new applications are also discussed.
关键词： Tungsten-bronze compounds,Ordering,Homologous series,Microwave dielectrics,Complex Perovskite
更新于2025-09-23 15:21:01
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Structural, Morphological, and Optical Properties of Iron Doped WO3 Thin Film Prepared by Pulsed Laser Deposition
摘要： The iron doped tungsten-oxide (Fe and WO3) thin ?lm with di?erent morphology and crystalline structures were obtained for di?erent substrate temperatures at the oxygen pressure of 14.66 Pa. The Fe-doped WO3 ?lms were deposited by pulsed laser deposition (PLD). The in?uence of the substrate temperature on the surface and on the crystalline phases of the ?lms was studied. The XRD (X-ray di?raction) analysis indicates the changing in the crystalline phases from γ-monoclinic to a mixture of γ-monoclinic and hexagonal phases dependent on the temperature of annealing and as-grown ?lms. Related to the as-grown and annealing ?lms conditions, the SEM (scanning electron microscopy) shows a change in the image surface from nanoneedles, to nanoporous, and further to long nanowires and broad nanobands. Energy-dispersive X-ray spectroscopy (EDX) shows the elemental composition of the Fe-doped WO3 ?lm as-grown and after annealing treatment. Raman spectroscopy presented the main vibration mode of the Fe-doped WO3 thin ?lm. The optical energy bandgap of the ?lms is decreasing as the substrate temperature increases.
关键词： PLD method,tungsten trioxide,Fe-doped WO3,structural and morphological characterization
更新于2025-09-23 15:21:01
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Hybrid Single-Layer/Bulk Tungsten Diselenide Transistors by Lithographic Encoding of Material Thickness in Chemical Vapor Deposition
摘要： whose bulk-like (3D) portion can be used for metal contacts and efficient charge injection into the metal dichalcogenide (TMD) transistors; because of the small number of charge carriers in a 2D demonstrate that lithographic pre-patterning of a growth substrate prior to chemical vapor deposition of a TMD film can shape the TMD material into nanoscale hybrid 2D/3D structures enhanced reduction of performance compared to conventional bulk Schottky Barriers. Here we single-layer (2D) areas which serve as transistor channels with excellent mobilities and on-off Schottky-like barriers are an important limitation of the performance of single-layer transition semiconductor, the screening of metal contacts is inefficient leading to large depletion zones and devices (through 300nm of oxide) at realistic operation temperatures near 100°C using ratios. We observe mobilities of nearly 100 cm2V-1s-1 with an on/off ratio >105 for bottom-gated TMD growth. Bulk-like 3D WSe2 is observed to grow at the location of the hafnia, while 2D comparatively long channels (>5 microns) and absent other contact optimization. Our process involves lithographic patterning of a hafnium (IV) dioxide film onto the SiO2/Si substrate prior to allows us to extract Schottky barrier heights and other fundamental properties of our hybrid single-layer material is grown in regions of bare SiO2. Systematic evaluation of transport data devices.
关键词： Tungsten Diselenide,Schottky-Barrier,Transition Metal Dichalcogenides,2D Materials
更新于2025-09-23 15:21:01
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Investigations of nano-crystalline Sr0.5Ba0.5Nb2O6 and bulk ceramics synthesized by a polymerization method using PEG400
摘要： Nano-crystalline Sr0.5Ba0.5Nb2O6 was synthesized by a one-pot method using PEG400 and citric acid. Calcination of the (Sr,Ba,Nb)-gel at 600 °C leads to Sr0.5Ba0.5Nb2O6 with a crystallite size of 24(2) nm and a specific surface area of 38.5(10) m2 g?1. Sintering up to 1325 °C leads to ceramics with globular or irregular-shaped grains and average grain sizes between 1.3 and 2.4 μm, whereas higher temperatures lead to a rod-like microstructure. The indirect allowed optical band gap varies between 3.70(5) and 3.29(5) eV. Dielectric measurements show a diffuse phase transition and weak relaxor properties. The maximum of the permittivity occurs between 116 and 147 °C. The frequency dependence of the impedance can be well described by one or two RC-circuits depending on sintering temperature. The melting temperature is determined as 1506(7) °C with ΔHf = 140(20) kJ mol?1. The average linear thermal expansion coefficient is found to be 10.5(5)?10?6 K?1.
关键词： Nano-particle,Strontium barium niobate,Band-gap,Dielectric permittivity,Tungsten bronze
更新于2025-09-23 15:21:01
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Application of Nanostructured Tungsten Fabricated by Helium Plasma Irradiation for Photoinduced Decolorization of Methylene Blue
摘要： The dendritic nanostructure was fabricated on a surface of tungsten plate by helium plasma irradiation. The nanostructure consisting of W metal was partially oxidized to form WO3 on exposure to air, and the resulting surface exhibited a broad photoabsorption in the range from 1 to 5 eV. We examined photoinduced reaction of methylene blue (MB) on the material. It was found that the partially and fully oxidized surface nanostructures were able to promote a decolorization of MB under photoirradiation even with the near-infrared light (< 1:55 eV), whose energy is lower than the band gap of WO3. The reaction rate was varied with the fraction of W and WO3 on the surface layers, that is, the partially oxidized sample promoted the reaction at a higher rate than the fully oxidized one. It is also found that the reaction rate decreased with time, which would be caused by the products accumulation on the surface and the surface oxidation.
关键词： Scanning electron microscopy (SEM),Tungsten oxide,Surface photochemistry,Plasma processing,Nano-wires, quantum wires, and nanotubes,Visible/ultraviolet absorption spectroscopy, X-ray photoelectron spectroscopy
更新于2025-09-23 15:21:01
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Properties, fabrication and applications of plasmonic semiconductor nanocrystals
摘要： In semiconductor nanocrystals (NCs), a new regime has been opened in the plasmonic field since the discovery of localized surface plasmon resonances (LSPRs). LSPRs that lead to near-field enhancement, scattering, and resonant absorption around the NC can be tuned in the range from the visible to the near-infrared (NIR) region across a wide optical spectrum by synthetically varying the doping level, and post synthetically via electrochemical control, photochemical control, and chemical oxidation and reduction. In this review, we will focus on the three widely explored and interrelated examples and their manipulation methods of LSPR of (1) hydrogen molybdenum bronze (HxMoO3?y) NCs, (2) hydrogen tungsten bronze (HxWO3?y) NCs, and (3) oxygen vacancy doped molybdenum tungsten oxide (MoxW1?xO3?y) NCs. Finally, a brief outlook on the applications of these plasmonic NCs is presented.
关键词： hydrogen molybdenum bronze,localized surface plasmon resonances,hydrogen tungsten bronze,plasmonic semiconductor nanocrystals,molybdenum tungsten oxide
更新于2025-09-23 15:19:57
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A new electrochemically prepared composite counter electrode for dye-sensitized solar cells
摘要： In this paper, we propose new counter electrodes for applications in dye-sensitized solar cells (DSSCs). Polyaniline (PANi), tungsten trioxide (WO3), and their composite are deposited on indium thin oxide substrates using cyclic voltammetry technique and employed as counter electrodes that reached comparable and superior performances than Pt counter electrodes. These excellent results are achieved due to the high conductivity and electrocatalytic behavior of the prepared materials. Morphological, electrocatalytic, bonding structure, charge transfer properties, and photovoltaic characteristics are respectively investigated by field emission electron microscopy, cyclic voltammetry, Tafel analysis, Fourier-transform infrared spectroscopy, UV-visible spectroscopy, energy dispersive spectroscopy, electrochemical impedance spectroscopy, and current-voltage analysis. Our best DSSC that is fabricated from the WO3/PANi nanocomposite counter electrode demonstrated an efficiency of 6.78%, which is a 12.4% improvement in comparison with the Pt-based DSSC.
关键词： Counter electrode,Tungsten trioxide,Cyclic voltammetry,Composites,Dye-sensitized solar cells,Polyaniline
更新于2025-09-23 15:19:57