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Switchable Bifunctional Bi-state Reusable ZnO-Cu for selective oxidation and reduction reaction
摘要： Herein we disclosed the utilization of copper loaded zinc oxide (ZnO-Cu) for its stimuli (O2/light) responsive switchable performance between its reduced (S-1) and oxidized (S-2) state for two antagonistic reactions, namely oxidation of alkyl arenes/heteroarenes to aldehydes/ketones and reduction of nitro arenes/heteroarenes to corresponding amines. The two states of the catalyst showed its switchable performance as highly active and poorly active catalyst for oxidation and reduction, and both reactions could be turned ‘off’ and ‘on’ by changing the stimuli (light and O2/N2). The switching efficiency between the states and their relative reactivity were found to be consistent under variety of reaction conditions and remain unaltered irrespective of oxidation-reduction (or vice versa) sequence and substrates used in the reaction. The photo catalysts (S-1 and S-2) demonstrated good catalytic activity, multiple reusability, broad substrate scope and reasonable functional group tolerance for both the reactions and probed its quality performance in a large-scale-set-up. The system was used in an assisted tandem catalysis set-up for the synthesis of benzyl amines utilizing both oxidation and reduction reaction by stimuli responsive switching between the states of the catalyst.
关键词： Switchable,Zinc oxide,Reusable,and Copper,Oxidation,Bi-State,Reduction
更新于2025-09-09 09:28:46
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Photocatalytic Decolorization of Cobalamin in Aqueous Suspensions of TiO2 and ZnO Under Solar Irradiation
摘要： Photolysis and photocatalysts treatments of aqueous solution of cobalamin were carried out over a suspension of titanium dioxide and zinc oxide. Heterogeneous photocatalytic processes applied under natural weathering conditions, in the presence of solar radiation show a promising degradation capability. Under solar radiation a complete removal of color was achieved in a relatively short time of about 10 minutes, when ZnO was used and in 45 min when TiO2 was used. However, in the presence of artificial UV-light, complete decolorization of cobalamin was obtained in 20 min of irradiation when ZnO was used and in 60 min, when TiO2 was used at the same temperature. The results indicate that the degree of photocatalytic decolorization of cobalamin was obviously affected by different parameters such as, catalyst mass, type of catalyst and addition of H2O2.
关键词： Titanium dioxide,Zinc oxide,Cobalamin,Solar,Photocatalytic reactions,Decolorization efficiency
更新于2025-09-09 09:28:46
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Preparation and Optical Property of Hierarchical Structured Porous ZnO Microplates
摘要： Hierarchical structured porous ZnO microplates have been prepared by thermal decomposition of Zn5(CO3)2(OH)6 precursor. The products are characterized by X-ray diffraction, field-emission scanning electron microscopy, high resolution transmission electron microscopy, transmission electron microscopy, UV-visible absorption spectrum and photoluminescence spectra. Each ZnO microplate is made up of nanoparticle-based nanowires with diameters of 40-80 nm and lengths of 2-3 μm and the diameter of constituent nanoparticles ranges from 10 to 20 nm. Due to their porous hierarchical microstructures, the prepared ZnO products exhibit excellent optical properties.
关键词： Zinc oxide,Porous microstructure,Optical property,Nanomaterials
更新于2025-09-09 09:28:46
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Design of Compresion Sensor by Zno Substrate using Precipitation Method
摘要： The Zinc Oxide nanoparticles are synthesized by the precipitation method using zinc acetate dehydrate and sodium hydroxide. The significance of characterization techniques like AFM, SEM, FTIR Spectrum and XRD for the prepared nanomaterial is studied. The prepared nanoparticles are used to improve the electrical conductivity of dielectric polymer like PMMA. Polymer metal Nano composites are prepared by in-situ oxidative polymerization of Methyl methacrylate monomer in the presence of different concentration of prepared metal nanoparticles. The electrical conductance is investigated using multimeter. The conductivity of the dielectric polymer is found to be increased with the increasing semiconductor concentration. Based on the result the prepared Nano composites can be used to convert the insulating foam into conductive one which can used to fabricate compression sensor.
关键词： wearable sensors,Zno- Zinc oxide,compression sensors
更新于2025-09-09 09:28:46
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Modular time division multiplexer: Efficient simultaneous characterization of fast and slow transients in multiple samples
摘要： A modular time division multiplexer (MTDM) device is introduced to enable parallel measurement of multiple samples with both fast and slow decay transients spanning from millisecond to month-long time scales. This is achieved by dedicating a single high-speed measurement instrument for rapid data collection at the start of a transient, and by multiplexing a second low-speed measurement instrument for slow data collection of several samples in parallel for the later transients. The MTDM is a high-level design concept that can in principle measure an arbitrary number of samples, and the low cost implementation here allows up to 16 samples to be measured in parallel over several months, reducing the total ensemble measurement duration and equipment usage by as much as an order of magnitude without sacrificing fidelity. The MTDM was successfully demonstrated by simultaneously measuring the photoconductivity of three amorphous indium-gallium-zinc-oxide thin films with 20 ms data resolution for fast transients and an uninterrupted parallel run time of over 20 days. The MTDM has potential applications in many areas of research that manifest response times spanning many orders of magnitude, such as photovoltaics, rechargeable batteries, amorphous semiconductors such as silicon and amorphous indium-gallium-zinc-oxide.
关键词： fast and slow transients,a-IGZO,MTDM,modular time division multiplexer,amorphous indium-gallium-zinc-oxide,parallel measurement,photoconductivity
更新于2025-09-09 09:28:46
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Unveiling the dual role of chemically synthesized copper doped zinc oxide for resistive switching applications
摘要： In this study, efforts were devoted to unveiling the dual role of single crystalline Cu (5%) doped ZnO (Cu:ZnO) synthesized by a simple and low-cost chemical process and to investigate its efficacy on resistive switching (RS) applications. It was found that when Cu:ZnO was annealed at a lower temperature of 450 °C and integrated onto ITO/glass for RS applications, only oxygen mediated vacancies were responsible for its resistive switching. However, ferroelectric properties have been observed when the same Cu:ZnO was annealed at a higher temperature of 800 °C and integrated onto Nb doped SrTiO3. X-ray diffraction, high resolution transmission electron microscope, x-ray photoelectron spectroscopy, UV-VIS-near infrared spectrometer, and piezoelectric force microscopy (PFM) were employed to study the crystallinity, interfaces, chemical compositions, bandgap, and domains in Cu:ZnO thin films, respectively. The bandgap of Cu:ZnO was found to be 3.20 eV. PFM study exhibits the domain inversion with 180° polarization inversion by applying an external bias, evidencing its effectiveness for memory applications. When the electrical characteristics were concerned, the RS device based on this ferroelectric Cu:ZnO offers better performance, such as lower SET/RESET voltages (～1.40 V), higher retention (up to 106 s) without distortion, and higher ON/OFF ratio (2.20 × 103), as compared to the former lower temperature annealed Cu:ZnO devices. A band-diagram was proposed, and transport studies were developed to understand the operational mechanism of these devices. This study explains both the limits and scopes of Cu:ZnO RS devices and formulates an idea which may accelerate the design of future generation devices.
关键词： copper doped zinc oxide,memory applications,band-diagram,resistive switching,ferroelectric properties
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE International Conference on Electron Devices and Solid State Circuits (EDSSC) - Shenzhen (2018.6.6-2018.6.8)] 2018 IEEE International Conference on Electron Devices and Solid State Circuits (EDSSC) - Dynamic Threshold Voltage Modulation in Double-Gate Indium-Gallium-Zinc Oxide Thin-Film Transistors: Influence of the Active Layer Thickness
摘要： We investigated the effect of active layer thickness on dynamic threshold voltage (VTH) operation for double-gate (DG) (a-IGZO) thin-film transistors (TFTs). It is found that with 80 nm a-IGZO layer, by adjusting top gate (TG) biases from negative to positive, the bottom gate (BG)-sweep TFTs show a VTH dependence on TG bias with two linear relationships, and subthreshold swing (SS) varies with different TG biases. In contrast, with thinner (20 nm) a-IGZO layer, VTH of the BG-sweep TFTs is linearly modulated with a single slope, and no obvious SS change is observed.
关键词： Thin-film transistors (TFTs),amorphous indium-gallium-zinc-oxide (a-IGZO),double-gate
更新于2025-09-09 09:28:46
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Effect of polyethylene glycol and propyltrimethoxysilane on structural and optical properties of zinc oxide nanoparticles synthesized by sol–gel process
摘要： Zinc oxide nanoparticles (ZnO NPs) are prepared by sol–gel process, using both polyethylene glycol (PEG-400) as surfactant and propyltrimethoxysilane (PTMS) as capping agent. Surface modi?cation is performed in situ procedure. The physical parameters such as strain and stress values are calculated via the Williamson–Hall plot (W&H) assuming a uniform deformation model (UDM) and uniform stress deformation model, and by the size and strain plot method (SSP). The results show that the crystallite size estimated from Scherrer’s formula, (W&H), (UDM), (SSP) and the particle size estimated from DSL are inter-correlated, which con?rm the small size and the isotropic nature of our ZnO NPs. The FTIR spectroscopy illustrates that PEG-400 and PTMS could be adsorbed at the ZnO NPs surface. The distinct emission peak in the blue band is located at 490 nm and E2 (high) mode is situated at 436 cm-1. Both results con?rm the oxygen de?ciency in the ZnO NPs.
关键词： Propyltrimethoxysilane,Sol–gel synthesis,Zinc oxide,Nanoparticles,PEG-400,DRX
更新于2025-09-09 09:28:46
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Hierarchical zinc oxide nanorings with superior sensing properties
摘要： Morphology controlled hydrothermal synthesis techniques have been realised to produce hierarchical zinc oxide (ZnO) nanostructures with high surface-to-volume ratios and more exposed polar facets. Hierarchical ZnO nanorings (HNRs) were produced by growing secondary nanowires (NWs) on initial mono-morphological nanodisks (NDs). In the two steps of growth process, zinc sulphate and zinc nitrate were used as the source of zinc ions, respectively. In comparison with NWs and NDs, the grown HNRs showed more enhanced performance as gas sensors. HNRs were substantially sensitive and faster in responding to acetone. This high performance in gas sensing is due to the increased surface-to-volume ratio and small size of the NW building blocks as well as the increased proportion of (0 0 0 1) polar facets. This work represents a guide to structure induced improvement of sensing properties by controlling the morphology of nanostructures.
关键词： Nanostructures,Sensor,Zinc oxide,Nanowires,Hydrothermal synthesis
更新于2025-09-09 09:28:46
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Electroluminescence of intrashell transitions in Eu doped single ZnO nanowires
摘要： Tunable nanoscale light emitters are essential to accomplish future multifunctional optoelectronic nano-devices. Here, we present an approach for achieving red electroluminescence from single ZnO nanowires implanted with Europium ions. The electroluminescence is emitted mainly from the end facets of ZnO nanowires at room temperature under the application of an AC voltage. The corresponding electroluminescence spectrum is attributed to the radiative intrashell transitions of the Eu ions, while contributions from near band edge or deep level emission of the ZnO remain absent. The total intensity of the electroluminescence is linearly proportional to the length of the nanowires, whereas there is no clear correlation with other morphology factors of the nanowire based device such as the diameter. Furthermore, the underlying excitation mechanism of the electroluminescence is proposed as direct-impact excitation of Eu ions by hot electrons in the ZnO nanowires.
关键词： electroluminescence,Zinc oxide (ZnO),Europium (Eu),nanowires,rare earth elements,ion beam doping
更新于2025-09-09 09:28:46