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Morphology Control of Hydrothermally Grown ZnO Nanostructures by Additives and Seed Layers
摘要： We present a rational control over the morphology of hydrothermally grown ZnO nanostructures by introducing different additives, sequential seeding, and multilayer seeds. The aspect ratio of the ZnO nanorods could be tuned with different types of additives (surfactant, amine, metal salt, and polymer additives) at an appropriate concentration in solution for ZnO hydrothermal growth. Some of the metal salts induced change in both aspect ratio and coverage simultaneously. The degree of vertical alignment of the ZnO nanowires was influenced by the number of seed layers. Furthermore, hierarchical ZnO nanostructures could be fabricated for thermal annealing on a secondary seed layer. The various control parameters demonstrated in this study provide beneficial information that can be used to guide a new strategy for relevant future applications.
关键词： Seed,Additive,Morphology,Hydrothermal,Zinc Oxide
更新于2025-09-23 15:22:29
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Sub-ppm acetone gas sensing properties of free-standing ZnO nanorods
摘要： In this paper, ZnO nanorods were synthesized by low cost and simple wet chemical method and used as a highly sensitive acetone gas sensor with detection limit as low as 25 ppb which makes the sensor a promising choice for various applications. The fabricated sensor showed a response value of 1.75 towards 25 ppb acetone at optimum working temperature of 320 °C with a response time of 30s. However, the sensor showed response value of 60 towards 50 ppm acetone with a response time of 15 s. The grown ZnO nanorods were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) for morphology and crystallinity characterization. According to the SEM images, freestanding nanorods with mean diameter of 80 nm and mean length greater than 1.5um were obtained with highly preferential c-axis orientation.
关键词： Sub-ppm sensing,Gas sensor,Acetone,ZnO Nanorods,Hydrothermal
更新于2025-09-23 15:22:29
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Magneto-Optical Effects in Colloidal Solutions of Barium Hexaferrite
摘要： Hydrothermal synthesis was used to obtain lamellar magnetic particles of barium hexaferrite, and colloidal solutions were prepared on their basis. Magneto-optical effects in colloid solutions of barium hexaferrite were examined. It was found that the aqueous colloidal solution of coarse planar particles of barium hexaferrite is a magneto-optical medium that is nearly two orders of magnitude more effective than the colloid formed from isometric cobalt ferrite particles. It was shown that measuring the frequency dependence of the magneto-optical effects and approximating the experimental data with the Debye function makes it possible to find the frequency f0 characteristic of the given colloid and to calculate the characteristic size of particles (or aggregates) creating the optical anisotropy in the colloid under the action of a magnetic field. A dichroism is observed in the aqueous colloid formed by coarse planar barium hexaferrite particles. This phenomenon is due to the change in the light scattering on coarse particles upon their orientation by a magnetic field.
关键词： lamellar magnetic particles,barium hexaferrite,colloidal solution,hydrothermal synthesis,magneto-optical effects
更新于2025-09-23 15:22:29
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Microwave Hydrothermal Synthesis of In <sub/>2</sub> O <sub/>3</sub> -ZnO Nanocomposites and Their Enhanced Photoelectrochemical Properties
摘要： Indium oxide (In2O3) doped zinc oxide (ZnO) nanocomposites were successfully synthesized through a facile microwave hydrothermal method. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption isotherms (BET) and UV-Vis diffuse reflectance spectroscopy. The morphology of In2O3-ZnO composites was observed to be like flowers, and the diameter of particles constituting the porous petal was about 30 nm. The photoelectrocatalytic test results showed that the photoelectrocatalytic methylene blue (MB) degradation efficiency using In2O3-ZnO nanocomposites as photocatalysts under visible light irradiation and a certain voltage could reached above 95.3% after 60 min, much higher than that of In2O3 particles and ZnO particles. The enhanced photoelectrocatalytic activity was attributed to the doping of In2O3 and applied voltage, which beneficially reduced the recombination of electrons and holes in the photoelectrocatalytic process, therefore, it promoted the production of active species (?OH and ?O2-).
关键词： photoelectrochemical properties,visible light irradiation,methylene blue degradation,In2O3-ZnO nanocomposites,microwave hydrothermal synthesis
更新于2025-09-23 15:22:29
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Synthesis of oxygen deficient bismuth oxide photocatalyst for improved photoelectrochemical applications
摘要： The present paper reports the effect of nitrogen modification on photoelectrochemical (PEC) water oxidation behavior of Bi2O3 semiconductor thin film. The semiconductor particles were synthesized via hydrothermal route using Bi(NO3)3 as a Bi3+ ion precursor and urea as the nitrogen source followed by drop-cast the particles and annealing the film at 600oC. The synthesized Bi2O3 exhibited band gap energy of 3.01 eV, calculated from the UV-vis absorption spectrum which decreases to 2.75eV through N-modification. Water oxidation behavior of the material has been tested through linear sweep voltammetry under periodic illumination. Highest photo-current of 180 μAcm-2 has been measured for water oxidation reaction at 0.95V vs. Ag/AgCl, under illumination of 35mWcm-2. N-incorporation can enhance the photocurrent up to 50% whereas the visible responsiveness of the material improves significantly as confirmed from electrochemical action spectra and UV-visible absorption spectra. The photocatalytic activity of the semiconductor particles was confirmed through decoloration of Rhodamine-B dye, by spectrophotometric measurements.
关键词： Hydrothermal synthesis,Oxygen vacancies,Bismuth oxide photocatalyst,PEC water oxidation.,N-modification
更新于2025-09-23 15:22:29
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A unique (4,4,5)-connected 3D zinc (II) metal-organic framework for highly efficient photodegradation of Rhodamine B under UV light
摘要： A new zinc (II) metal-organic framework, [Zn3(L)2(nbta)2]n (1) (L = 1,4-bis(benzimidazol-1-yl)-2-butene, H3nbta = 5-nitro-1,2,3-benzenetricarboxylic acid) was hydrothermally synthesized and structural characterized. 1 possesses a unique 3D (4,4,5)-connected network with a Schl?fla symbol of {42.63.8}2{44.62}{47.63}2. Furthermore, the photocatalytic property of 1 for degradation of the Rhodamine B (RhB) was examined under UV irradiation.
关键词： Semi-rigid bis(benzimidazole),Hydrothermal synthesis,Crystal structure,Metal-organic framework,Zinc (II),Photocatalytic degradation
更新于2025-09-23 15:22:29
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Effect of pH on the Properties of BiVO<sub>4</sub> by Hydrothermal Synthesis Method
摘要： Bismuth vanadate (BiVO4 ) powders were synthesized using Bi(NO3)3.5H2O and NH4VO3 as raw materials, NaOH and HNO3 for pH adjustment. The samples were characterized by X-ray diffraction ( XRD ), scanning electron microscopy (SEM ) and UV-vis diffuse reflectance spectra techniques. The results show that the pH of precursor solution has great effect on the composition and morphology of products. Synthetic product was BiVO4 with two kinds of crystal shape ( monoclinic and tetragonal ) with pH of 3; synthetic product was pure monoclinic phase BiVO4 when the pH is between 5-9. Whereas, V2O5 and Bi2O3 appeared when the pH was 11; synthetic product was a mixture of V2O5 and Bi2O3 with pH of 13, and BiVO4 didn’t exist. The photocatalytic activity was evaluated by the degradation of methylene blue solution. It is shown that the synthetic sample has the best photocatalytic ability with pH of 5. The degradation of methylene blue reaches 84.7% when irradiated for 240 min by high pressure mercury lamp, and the sample synthesized at 13 for pH has strong adsorption capacity and poor photocatalytic ability.
关键词： Bismuth vanadate,Photocatalytic activity,pH value,Hydrothermal synthesis
更新于2025-09-23 15:22:29
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Enhanced UV-light driven photocatalytic performances and recycling properties of TiO2/AlON composite photocatalyst
摘要： AlON has been reported to have photocatalytic capability under ultraviolet-light (UV-light), which can be improved by fabricating large-sized powder (~20 μm) having porous skeleton microstructure. To further enhance photocatalytic property of AlON, highly photocatalytic-efficient nanocrystalline TiO2 was loaded onto both the outer and inner surface of porous AlON particles by hydrothermal method. In order to ensure easy recovery without secondary pollution, the obtained composite powder was filtered in deionized water three times to remove both small-sized AlON and free TiO2 particles to produce a composite photocatalyst with particle size > 10 μm. The proposed TiO2/AlON showed excellent photocatalytic performance on Methylene blue (MB) and Methyl orange (MO) for 97.9% and 99.1% of pollutants (in 30 mg/L, 40 mL solution) being degraded by 50 mg as-synthesized composite photocatalyst in 120 min. Further test showed that the hydrothermal process can significantly improve the photocatalytic performance of TiO2/AlON composite photocatalyst and its enhancement mechanism were discussed. In addition, the large-sized composite photocatalyst is easy to recover and stable to reuse with no regeneration needed.
关键词： Hydrothermal method,Composite photocatalyst,TiO2/AlON,UV-light
更新于2025-09-23 15:22:29
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Enhanced Ultraviolet Emission from Hydrothermally Grown ZnO Nano-Grass on Si Substrate
摘要： Highly crystalline one-dimensional zinc oxide (ZnO) nano-grass was grown on silicon (Si) substrate by a modified hydrothermal method. A predominantly c-oriented ZnO nano-grass with an average diameter of 40–60 nm and length of 1.5–2.0 lm was obtained. From the photoluminescence (PL) measurement, we observed a defect-free, intense ultraviolet emission of as-grown ZnO nano-grass, confirming the absence of singly ionized oxygen vacancies. The absence of green deep-level emission in the PL spectrum further implies a high crystallinity of as-grown ZnO nano-grass. The high-quality ZnO nano-grass has potential applications in single nanowire-based light-emitting diodes, solar cells, themoresistive sensing, photocatalysis, ultraviolet photodetectors, optical switches, waveguides and nano-lasers.
关键词： photoluminescence,ZnO nanowires,annealing process,ultraviolet emission,hydrothermal method
更新于2025-09-23 15:22:29
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Synthesis of Mn doped ZnO nanopowders by MW-HTS and its structural, morphological and optical characteristics
摘要： In this study, undoped and Mn doped ZnO nanopowders were synthesized by using the microwave assisted hydrothermal (MW-HTS) method. Doping ratio of Mn in the ZnO was set to 1, 5 and 10%. The effect of Mn concentration on the structural and morphological properties of ZnO nanopowders was investigated using XRD, SEM, XPS and FTIR. XRD results showed that the nanopowders have hexagonal wurtzite structure. The lattice parameters increased with increasing Mn incorporation. SEM images showed that all the samples were formed in nanorod structure and the average diameter of the rods decreased with the Mn concentration. XPS results veri?ed the presence of Mn as a doping element into ZnO crystal lattice and the oxidation states of Mn and Zn. The chemical interactions of ZnO and ZnO:Mn nanopowders were determined for using FTIR spectrum.
关键词： FTIR,Mn doped ZnO,XPS,Microwave assisted hydrothermal,Nanorods
更新于2025-09-23 15:22:29