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Using the sol–gel auto combustion method with diethanolamine (DEA) as fuel, a sequence of iron‐substituted zinc aluminates, ZnFexAl2‐xO4 powders, including variable Fe3+ ion concentrations (0 ≤ x ≤ 2) were effectively prepared. X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), the Brunauer–Emmett–Teller (BET) method, UV–visible diffuse reflectance spectroscopy (UV‐DRS), and vibrating sample magnetometer (VSM) were employed to examine the structures, chemical bonds, morphologies, composition, surface area, and optical properties as well as the magnetic behavior of the obtained samples. A single‐phase spinel structure was obtained for the calcined aluminate powders with different interplanar spacing and crystallite sizes, as revealed by the classification results. The bandgap energy (Eg) of adapted aluminates was in the range of 2.04‐3.14 eV, identified as being much lower compared to the pure sample (5.60 eV). Thus, Fe3+‐substituted ZnAl2O4 samples could be successfully photoexcited using both ultraviolet and visible light, as suggested by the results. Examination of how the four main pollutant types decay when irradiated by sunlight was carried out to assess the samples and establish photocatalytic activity. These contaminants included rhodamine B (RhB), methylene blue (MB), methyl orange (MO), and methyl red (MR). The performance of photocatalytic degradation reached 98% after 150 min for all optimal samples of organic dyes. Besides, each of the altered photocatalysts could be recycled and displayed high stability. The S‐shaped curve of ferrimagnetism can result in those samples as found by the magnetic measurements, though pure ZnAl2O4 displays diamagnetic characteristics. The adapted samples show intense improvement in the remanent magnetization (Mr) when compared to pure ZnAl2O4, signifying that magnetic photocatalyst recovery by applying an external magnetic field is easy. Thus, these results offer a convincing sign that ZnAl2O4 powders replaced by Fe3+ could provide the ability to aid in the ecologically friendly collection of solar energy. [ABSTRACT FROM AUTHOR]

The visible light responding TiO2 nanoparticles have been achieved through green synthesis method. In this experiment, three types of natural dyes including Turmeric extract, Bergamot fruit extract, and Siamese neem leave extract were used as stabilizing agents. TiO2 nanoparticles were synthesized by solution-based one-step and two-step methods. The results of X-ray diffraction (XRD) and Ti K-edge X-ray absorption near edge structure (XANES) spectroscopy affirmed that anatase TiO2 nanoparticles were obtained from all samples with the average crystallite sizes of 5-8 nm. Moreover, UV-Visible absorption spectra revealed that the natural dyes play an important role in improving the visible light absorption ability of TiO2 and decreasing the band gap energy of TiO2 from 3.1 eV to 2.3 eV. The absorption edge energies of the two-step samples were lower than those of the one-step samples. The infrared spectra of the two-step TiO2 displayed complex vibration features which were related to the carbonyl (C=O) and hydroxyl (O=H) groups of natural dyes. The presence of these functional groups was obviously responsible for the optical response of TiO2 nanoparticles in the visible wavelength region. [ABSTRACT FROM AUTHOR]

Nanocrystalline NiAl2O4, CuAl2O4 and ZnAl2O4 aluminate spinels were successfully synthesized by the sol-gel auto combustion method using diethanolamine as a novel fuel. The structures, morphologies, particle sizes, and optical properties of these aluminate particles were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and UV-Visible diffuse reflectance spectroscopy (UV-DRS). All characterization results confirmed that a single-phase spinel structure was obtained for all calcined aluminate powders with various crystallite sizes (40-60 nm) and distinct band gap energies, Eg (3.0-5.5 eV). The photocatalytic activity of NiAl2O4, CuAl2O4 and ZnAl2O4 nanoparticles were evaluated by the decomposition of four types of pollutants: phenol rhodamine B, heteropolyaromatic methylene blue, azoic methyl orange, and methyl red under ultraviolet irradiation. The photocatalytic degradation efficiencies of all organic dyes by aluminate spinels reach 80-95% within 100 min. These results suggested that NiAl2O4, CuAl2O4 and ZnAl2O4 can serve as photocatalysts for the degradation of a wide range of organic pollutants in environment. [ABSTRACT FROM AUTHOR]

Binary metal pyrophosphates; Cu(2-x)ZnxP2O7(x= 0.0–2.0) compounds, were prepared via the solid solution method. The synthesize powders were characterized by X-ray diffraction (XRD). The local structure of Cu was analyzed by the mean of synchrotron X-ray absorption near the edge structure (XANES). The Cu2+-O1, Cu2+-O2 and Cu-Cu/Zn distances determined are extended X-ray absorption fine structure (EXAFS) measurements at the Cu K-edge, with a distance of about 1.52, 2.11, and 2.74 Å. The correlation between the structural changes and Cu content was analyzed and discussed. The analysis of the EXAFS spectra collected at the Cu K-edge indicates that the local structure around Cu atoms also is affected by the introduction of Zn atoms in the structure. [ABSTRACT FROM PUBLISHER]

Ina previous study, we confirmed by in situ combined high-resolutionpowder diffraction/X-ray absorption spectroscopy and Raman scatteringexperiments that the crystal formation of the well-known γ-Bi2MoO6catalyst occurred in two steps through theformation of an intermediate fluorite structure (Kongmark, C.Chem. Commun.2009, 4850−4852; Catal. Today2010, 157, 257–262). Here, for the first time, by combining these resultswith complementary ex situ studies (HTXRD, SEM/EDX, Raman scattering),it was possible to elucidate the nature of the intermediate phaseand to propose a complete scenario of the growth of γ-Bi2MoO6crystals. In addition, we performed a kineticanalysis from the three different in situ characterization techniquesand confirmed a 2D-diffusion limited growth process. [ABSTRACT FROM AUTHOR]

The article discusses the oxygen diffusion mechanism in BIMEVOX and Brownmillerite materials. The two materials have high oxide ion conduction owing to their layered structure with intrinsic oxygen vacancies. The results of a study which utilized atomistic simulation, X-ray diffraction, neutron diffraction, impedance spectroscopy, among other techniques, to investigate the transport of oxygen in these two families of materials are presented.

Combination of in situ Raman scattering with high-resolution XRD and XAS techniques has proven to be a powerful tool to elucidate the crystal growth of γ-Bi2MoO6 under hydrothermal conditions. [ABSTRACT FROM AUTHOR]

Combination of in situRaman scattering with high-resolution XRD and XAS techniques has proven to be a powerful tool to elucidate the crystal growth of γ-Bi2MoO6under hydrothermal conditions. [ABSTRACT FROM AUTHOR]

Herein, the single‐phase Ni‐based bimetallic spinel oxide (NiM2O4, M = Mn, Fe, Co) nanoparticles are successfully synthesized by sol–gel method and coated on a carbon cloth substrate to form flexible electrodes for supercapacitor applications. The effects of transition metal activity, calcination temperature, surface, and textural properties on the electrochemical properties of spinel electrode materials are demonstrated. It is found that lowering the calcination temperature results in a decrease in crystallite size and particle size, leading to an increase in surface area and pore volume. X‐Ray absorption spectroscopy reveals the presence of Mn2+/3+, Fe2+/3+, and Co2+/3+ in materials. According to the electrochemical studies, NiMn2O4 electrode in Na2SO4 electrolyte exhibits electrical double‐layer capacitance behavior, while NiFe2O4 and NiCo2O4 electrodes in KOH electrolyte exhibit pseudocapacitive behavior. All electrode materials have low solution resistance and charge transfer resistance. NiCo2O4 provides the highest specific capacitance (85.60 F g−1 at 2.5 A g−1) followed by NiFe2O4 and NiMn2O4. It seems likely that the high electrochemical activity of Co2+/3+ and small particle size of NiCo2O4 nanoparticles play an important role in improving the redox process and charge transfer, which may enhance the electrochemical performance of this electrode material. [ABSTRACT FROM AUTHOR]

Catalytic behaviors of copper phosphide supported on various oxides (SiO2, γ-Al2O3, and USY zeolite) have been evaluated for deoxygenation of oleic acid and compared with nickel and cobalt phosphides. All catalysts were prepared by the hydrogen reduction of metal phosphate precursors. CoP and Ni2P were obtained on USY zeolite, while Cu3P was formed on USY and SiO2 supports. On the contrary, the metallic Cu phase was stabilized on γ-Al2O3 support. Metal phosphide particles were highly dispersed on the USY support. Cu3P/USY exhibited much larger surface area and higher acidity compared to Cu3P/SiO2, owing to the textural and acidic properties of the USY zeolite support. All supported catalysts gave an oleic acid conversion close to 100% at 340 °C. Ni2P/USY, CoP/USY, and Cu/γ-Al2O3 favored the deoxygenation of oleic acid to alkane products such as heptadecane and octadecane. Highly selective production of octadecane (98%) through hydrodeoxygenation pathway occurred on Cu/γ-Al2O3. In contrast, the supported Cu3P catalysts favored cyclization and aromatization to form cyclic and aromatic compounds such as dodecylcyclohexane, heptylcyclopentane, and dodecylbenzene. Cu3P/SiO2 provided dodecylbenzene in higher yield (46%) than Cu3P/USY (33%). [ABSTRACT FROM AUTHOR]

Abstract: The actual oxygen environment of the tungsten dopant in the Ba2In2− x W x O5+3 x /2 solid solution was revealed by combining X-ray absorption spectroscopy at the tungsten L I and L III edges and at the indium L I edge. Whatever the substitution ratio, the tungsten atoms exhibit a regular octahedral environment. When the substitution ratio increases, the oxygen vacancies are progressively filled until their total occupancy for x=2/3. For x⩾0.3, the perovskite structure is stabilised; the tungsten atoms are randomly distributed in the structure. Although X-ray diffraction revealed a cubic symmetry for these compositions, a local distortion of the indium environment is observed when a tungsten atom is in its surrounding. [Copyright &y& Elsevier]