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Degradation of benzothiophene in diesel oil by LaZnAl layered double hydroxide: photocatalytic performance and mechanism
摘要： A new type of photocatalytic La3+–Zn2+–Al3+–MoO4 2- layered double hydroxide (LDH) material (molar ratio, La/Zn/Al = 1:7:2) was prepared by a complexing agent-assisted homogeneous precipitation technique. The structure of the prepared LDH material was systematically studied. Under UV irradiation, the desulfurization efficiency of the LDH material was 87% in 2 h. For La3+–Zn2+–Al3+–MoO4 2- LDH material, the introduction of MoO4 2- increased the interlayer space for promoting the adsorption of benzothiophene (BT), and MoO4 2- might provide active sites for the oxidation of BT, resulting in the high desulfurization efficiency.
关键词： Photocatalytic activities,Catalytic oxidation mechanism,LDH,Homogeneous precipitation
更新于2025-09-23 15:23:52
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Structural, optical, and dielectric properties of Cu, Ni-doped Zn ferrites
摘要： Ferrite nanocomposites with the composition Cu0.5Zn0.5Fe2O4 and Ni0.5Zn0.5Fe2O4 were prepared by co-precipitation method. The effect of dopant to spinel ferrite ZnFe2O4 on the structural, morphological, optical, and dielectric properties of the as-prepared Cu-Zn and Ni-Zn ferrites were investigated. The structural, elemental, and optical properties conducted by using X-ray diffraction (XRD) technique with Cu/Kα radiation, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), Raman spectroscopy, and UV–Vis reflectance spectroscopy. For the electrical properties of the Cu-Zn and Ni-Zn ferrites, a real part of the dielectric constant and AC conductivity have been investigated with a frequency range of 20 Hz to 10 MHz at different temperature for each sample. The substitutions of Cu and Ni into the ZnFe2O4 nanocomposites crystal size calculated 20.36 nm for Cu-Zn ferrite and 10.95 nm for Ni-Zn ferrite. Also, the energy band gap of Cu-Zn ferrite is 2.6 eV and Ni-Zn ferrite is 2.83 eV. These results show that the energy band gap is increased when the crystal size is reduced by the substitution of Ni into the Zn ferrite. The dielectric constant and AC conductivity of Cu-Zn ferrite is bigger than the Ni-Zn ferrite at low frequencies. This situation is related to the structural parameters. Also, the AC conductivity increases with an increasing frequency and temperature.
关键词： AC conductivity,Co-precipitation,Cu-Zn ferrites,Dielectric constant,Ni-Zn ferrites
更新于2025-09-23 15:22:29
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Cu(OH)2 Nanostructures for Dynamic Photodegradation of Methyl Orange under Visible Light
摘要： A new material of Cu(OH)2 nanostructures was prepared using cupric nitrate and sodium hydroxide as raw materials by the chemical precipitation method. The Cu(OH)2 nanostructures were characterized by scanning electron microscope, transmission electron microscopy, infrared spectrometer, and X-ray diffractometer. The results showed that the Cu(OH)2 nanostructures exhibited excellent uniform and dispersion at 40°C. A series of factors was investigated to effect the photocatalytic efficiency of methyl orange (MO), such as the concentration of Cu(OH)2 nanostructures, the reaction time of the Cu(OH)2 nanostructures, the initial concentration of MO, and so on. As a result, the Cu(OH)2 nanostructures exhibited excellent photocatalytic efficiency with the concentration of 20 mg L–1 Cu(OH)2 nanostructures, the initial concentration of MO was 15 mg L–1 and the stirring time was 70 min.
关键词： photocatalytic efficiency,chemical precipitation method,Cu(OH)2 nanostructures
更新于2025-09-23 15:22:29
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Comparative study of structural, magnetic and dielectric properties of CoFe2O4 @ BiFeO3 and BiFeO3@ CoFe2O4 core-shell nanocomposites
摘要： Nano-sized CoFe2O4 (CFO), BiFeO3 (BFO) and their core-shell composites BFO@CFO and CFO@BFO were synthesized by chemical co-precipitation method. X-ray di?raction pattern con?rmed the crystallinity and phase formation of bare CFO, BFO and their core-shell composites. Morphology and core-shell nature of these nano-particles is justi?ed by ?eld emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Magnetization curve showed the weak ferromagnetic behaviour of BFO. Typical ferrimagnetic behaviour is shown by bare CFO and core-shell nanocomposites. The value of maximum magnetization, remanence magnetization and coercivity of CFO@ BFO were found to be greater than the BFO@ CFO. Also, CFO@ BFO showed the highest value of dielectric constant in the frequency range of 104–106 Hz. Dielectric constant versus temperature curve of BFO and core-shell composites exhibit incongruity close to the anti-ferromagnetic transition temperature (370 °C) of BFO indicating presence of magnetoelectric (ME) coupling.
关键词： Multiferroic,Nanocomposite,Core-shell,Co-precipitation
更新于2025-09-23 15:21:21
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Effect of the Synthesis Method on the Properties of Ultrafine YAG Powder
摘要： Yttrium aluminum garnet (YAG) materials have a number of unique properties, such that its application is extensive. In this study, ultrafine YAG powder materials were prepared by coprecipitation and hydrothermal precipitation methods. The influence of the synthesis process on the morphology of the powder was investigated. Results showed that the precursor powder prepared via the coprecipitation method mainly undergoes amorphous to crystalline transition with the increase in calcination temperature and that the precursor agglomeration is severe. In the process of increasing the calcination temperature, the dispersibility of the roasted powder is considerably improved, which is favorable for the growth of the crystal grains, such that the particle size of the powder is gradually increased. The YAG precursor prepared by the coprecipitation method is transformed into YAG crystals, with the phase transition mainly occurring between 900 °C and 1,100 °C. When the molar ratio of salt to alkali is Y3+/OH?=1:8 via the hydrothermal reaction, YAG particles with homogeneous morphology can be obtained. When the molar ratio of salt to alkali is continuously increased, the morphology of YAG particles is not obviously changed. The coprecipitation method is used to control the particle size, whereas the hydrothermal method is used to control the particle morphology.
关键词： co-precipitation method,hydrothermal precipitation method,ultra-fine powder,YAG
更新于2025-09-23 15:21:01
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Investigating the Photovoltaic Performance of Surfactant assisted MoBi2Se5 Thin Films
摘要： MoBi2Se5 has been proved to be a promising material for the photoelectrochemical solar cell application. As, MoBi2Se5 thin films are more corrosion resistant than Bi2Se3 thin films also MoBi2Se5 can be used as a buffer layer due to its distinctive optostructural properties. In this study, we have synthesized surfactant assisted nanostructured MoBi2Se5 thin films by using cost effective chemical route, i.e. arrested precipitation technique (APT). The synthesized thin films were analyzed for their Opto-structural, surface morphological, compositional and photovoltaic application using X-ray diffraction Technique (XRD), UV-Vis Spectroscopy, Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX) and its photoelectrochemical solar cell performance was checked respectively. The nanocrystalline nature of MoBi2Se5 thin films was confirmed from the XRD pattern. An increment in the optical band gap energy was observed with surfactant mediation. The surface morphology of MoBi2Se5 was changed from spherical to spongy balls like nanofibrous surface morphology after surfactant assistant. Furthermore, both the as synthesized and surfactant assisted MoBi2Se5 thin films showed the photoelectrochemical solar cell applicability.
关键词： thin films,arrested precipitation technique,MoBi2Se5,surfactant,photoelectrochemical solar cell
更新于2025-09-23 15:21:01
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Light Bullets in Passively Mode-Locked Lasers: Dynamics and Instabilities
摘要： Vertically and horizontally inhomogeneous distributions of hydrometeors are often observed in precipitating clouds. The 3-D characteristics can then cause errors in the passive microwave rainfall measurements with the current off-nadir viewing sensors’ specific specifications. This result is due to the fact that the same surface rainfall could be associated with different amounts of hydrometeors depending on the sensors’ viewing paths. In this paper, we confirmed that the plane-parallel radiative treatment to the atmosphere leaves a notable deficiency in the microwave radiometric signatures, particularly at the higher frequency channels for different viewing directions when largely inhomogeneous precipitating clouds are accompanied by significant ice particles. The mean differences between the two brightness temperature fields with two opposite azimuthal viewing directions were up to approximately 40 ?K for the vertically polarized channel at 85.5 GHz in the case study. The impact of the 3-D effect on the passive microwave rainfall estimations was also examined by synthetic retrievals employing a Bayesian methodology. The results showed that the uncertainty in the rainfall estimations due to the 3-D effect depended on the viewing directions considered in the a priori information. It was also found that taking more viewing angles or the azimuth angles in the a priori information into consideration tended to moderate the retrieval difference that resulted from the different viewing directions. In addition, the retrieval uncertainty related to the 3-D effect appeared to be more significant for heavy rainfall cases with large amounts of ice particles, as expected.
关键词： 3-D radiative transfer,precipitation,3-D effect,Passive microwave remote sensing
更新于2025-09-23 15:21:01
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Observations of phonon anharmonicity and microstructure changes by the laser power dependent Raman spectra in Co doped SnO2 nanoparticles
摘要： SnO2 nanoparticles are of critical importance owing to their necessity for fundamental studies and highly attractive applications in optoelectronic devices and photocatalytic activities. In this study Raman spectroscopy was rigorously employed to investigate the effect of low concentrations of cobalt doping in rutile SnO2 nanoparticles. The effect of annealing temperature and laser power dependent molecular vibrations was used to directly realize the localized microstructural changes and phonons interaction within the lattice. A large broadening and shifting towards the lower wavenumber side in the Raman spectra for A1g and B2g modes of vibration were observed. This was mainly attributed to microstructural changes, maximum possible quasiharmonic shift and a large proportion from pure anharmonic shifts as a function of increasing laser power. Two approaches were adopted to calculate the localized temperature that has increased due to laser heating during the Raman measurements in the samples. In a more feasible and reliable approach the full with at half maxima (FWHM) broadening and frequency shifting as a function of laser power were directly compared with the previously reported experimental results. In another approach the well-known Klement model based on the kinematics of three-phonon processes was also used to determine the localized temperature.
关键词： Raman,Cobalt,Nanoparticles,SnO2,Laser,Co-precipitation
更新于2025-09-23 15:21:01
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Chiral Helical Polymer Nanomaterials with Tunable Morphology: Prepared with Chiral Solvent To Induce Helix-Sense-Selective Precipitation Polymerization
摘要： We report an unprecedented strategy for using achiral monomer to construct chiral helical polymer nanomaterials with tunable morphology—helix-sense-selective precipitation polymerization induced by a chiral solvent (HSSPP-CS). CHCl3, chiral α-pinene, and an alkanol were employed to constitute a solvent mixture for performing HSSPP-CS. (R)- or (S)-α-pinene worked as chiral source and transferred its chirality to the resulting helical polyacetylenes derived from achiral monomer in the course of polymerization, thereby forming chiral helical polymers and endowing the nanomaterials thereof with optical activity. Simply changing solvent composition provided chiral polymer products varying in morphology from fibrous to rod-like and finally to spherical morphology. This is the first report dealing with chirality transfer from chiral solvent to induce helix-sense-selective precipitation polymerizations. The study establishes a straightforward and effective alternative for making use of achiral monomers to construct chiral helical polymer nanomaterials with diverse morphology.
关键词： tunable morphology,chiral solvent,achiral monomer,chiral helical polymer nanomaterials,helix-sense-selective precipitation polymerization
更新于2025-09-23 15:21:01
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ZnO/Ag NANOPARTICLE-DECORATED SINGLE-WALLED CARBON NANOTUBES (SWCNTs) AND THEIR PROPERTIES
摘要： Raw single-walled carbon nanotubes (SWCNTs) were oxidized by using sulfuric acid and nitric acid at 3:1 ratio to produce oxygen functional groups attached to SWCNTs surfaces. Then, the oxidized SWCNTs are coated with zinc oxide and silver nanoparticles by chemical precipitation route to synthesize ZnO/Ag-SWCNTs nanocomposite material. The nanocomposite sample was analyzed via zeta potential analyzer, ultraviolet-visible (UV-Vis) spectrophotometer, ˉeld emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray di?raction (XRD), and Raman spectroscopy to investigate colloidal stability, optical, morphological, and structural properties. The SWCNT properties were found to be changed after the addition of ZnO/Ag nanoparticles. Hence, the new ZnO/Ag-SWCNTs nanocomposite is a good candidate for photocatalyst applications and biological applications.
关键词： biological applications,photocatalyst applications,Single-walled carbon nanotubes (SWCNTs),ZnO/Ag nanocomposite,chemical precipitation
更新于2025-09-23 15:21:01