Bismuth tungstate Bi 2 WO 6 : a review on structural, photophysical and photocatalytic properties

This review paper provides a comprehensive overview of the recent trends in bismuth tungstate (Bi 2 WO 6 ) research, covering its structural, electrical, photoluminescent, and photocatalytic properties

Electrical impedance spectroscopy analyses and optical properties of the bismuth lutetium tungstate BiLuWO 6

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Novel Lu-doped Bi2WO6 nanosheets: Synthesis, growth mechanisms and enhanced photocatalytic activity under UV-light irradiation

International audiencePolycrystalline systems of lutetium doped bismuth tungstates Bi2WO6: Lu (Lu at% 0, 2, 5 and 8) were synthesized using the coprecipitation method, followed by thermal treatment at 500 degrees C. The Bi2WO6:Lu samples were characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDS) and UV-vis diffuse reflectance spectra (DRS). The XRD and SEM analyses showed that the as-prepared samples crystallized in the same orthorhombic structure and consist of agglomerated nanosheets. To characterize the photocatalytic activities, UV-visible spectrometry was used to analyze the evolution of Rhodamine B photodegradation in presence of the Bi2WO6: Lu photo catalysts. The characteristic absorption band of Rhodamine B at 554 nm shifted to lower wavelengths under UV irradiation. The pure Bi2WO6 and the 5% Lu doped Bi2WO6 photocatalysts presented the lowest and highest efficiencies, respectively. An interpretation of improved photocatalytic efficiencies was proposed. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Novel Lu-doped Bi2WO6 nanosheets: Synthesis, growth mechanisms and enhanced photocatalytic activity under UV-light irradiation (vol 42, pg 8552, 2016)

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Effects of lutetium doping on the X-ray-excited luminescence properties of the tungstate Zn1-xLuxWO4

International audiencePolycrystalline samples in the lutetium-doped zinc tungstate system Zn1-xLuxWO4 with 0 <= x <= 0.08 were synthesized using the coprecipitation method followed by thermal treatment at 1000 degrees C during 4 h. The polycrystalline samples were characterized by X-ray diffraction analysis, scanning electron microscopy (SEM), infrared spectroscopy, and luminescence analysis under X-ray excitation. Rietveld analyses were performed. The variation of the wolframite structure cell parameters in the range 0 <= x <= 0.05 were congruent with substitution of Zn2+ by Lu3+. SEM micrographs of the obtained samples presented improved crystallization with morphology depending on the lutetium fraction. The luminescence spectra obtained under X-ray excitation (E < 40 keV) were in the blue-green region, and their intensity increased with x up to x = 0.05. The differences in the intensities of the X-ray luminescence spectra could be related to additional cation vacancies resulting from substitution of Zn2+ by Lu3+

Low-temperature synthesis, characterization and photocatalytic properties of lanthanum vanadate LaVO4

In this study, we have successfully prepared tetragonal lanthanum vanadate LaVO4 nanoparticles by a facile co-precipitation method at room temperature. The obtained materials were characterized using different structural and micro-structural techniques such as the characterization by X-ray diffraction (XRD), UV–Vis diffuse reflectance spectrum (DRS), transmission electron microscopy (TEM), and Raman spectrometry. The obtained structure is crystallized in single tetragonal phase with pin-like nanostructure. A main optical transition with bandgap energy of 3.26 eV is evidenced, and the average lifetime of charges carriers was found to be 1 ns Furthermore, the photoluminescence occurs in the visible light range. The photocatalytic activity was evaluated by the photocatalytic degradation of methylene blue (MB) with initial concentration of 10 mg L−1. The result indicates that LaVO4 particles showed a best photocatalytic activity of 98.2% degradation for methylene blue solution after irradiation of 90 min under visible light. Furthermore, the photocatalytic mechanism and reusability were studied

Electronic band structure and visible-light photocatalytic activity of Bi2WO6: elucidating the effect of lutetium doping

International audienceBismuth tungstate and 5% Lu-doped bismuth tungstate photocatalysts were synthesized by coprecipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra (DRS), and Brunauer-Emmett-Teller (BET) surface area. The effect of lutetium doping on electronic structure was investigated using density functional theory calculations (DFT). The change of morphological and optical band gap was conditioned by lutetium doping. Under visible light irradiation, the as-prepared sheet-like Lu-Bi2WO6 sample exhibits the highest visible-light-responsive photocatalytic performance than pure Bi2WO6 for the degradation of Methylene Blue (MB). The photocatalytic mechanism was explained on the basis of electrochemical impedance spectroscopy (EIS), photoluminescence (PL) spectra, active trapping measurements and optoelectronic properties

Rietveld refinements, impedance spectroscopy and phase transition of the polycrystalline ZnMoO4 ceramics

International audienceThe triclinic phase of zinc molybdate ?-ZnMoO 4 (ZMO) was synthesized by a simple co-precipitation method at 600°C. The crystal structure of the obtained polycrystalline sample of ZMO was characterized by X-ray diffraction (XRD) and Rietveld calculations using the space group P-1. The electrical properties of ?-ZnMoO 4 compacted pellets were determined at room temperature from Electrical Impedance Spectrometry (EIS), in the temperature range of 400°C to 700°C. Nyquist representations were interpreted in terms of two types of electrical circuits, involving a high frequency bulk component and a low frequency Warburg component. Analyses of the frequency dependence of the real and imaginary impedance show a non-debye type relaxation. A phase transition corresponding to the allotropic transformation triclinic-monoclinic (α?β) of ZnMoO 4 was observed in the temperature range of 450 to 500°C, with a variation of activation energies. The Warburg component is discussed in terms of electrode surface reactions