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This study is a contribution to development of material based on transition metal oxides with application in electrochemical devices. A pyrochlore-like solid solution with general chemical formula Bi1.2Ce0.3Sb1.5CuO7 was synthesised. The pyrochlore structure was determined by X-ray powder diffraction. The pressed pyrochlore powder sample was analysed by scanning electron microscopy to show effect of substitution fraction of cerium and to determine its grain size and morphology. Energy dispersive of X-rays was performed to confirm effective substitution of bismuth for cerium. The EDX analysis was supported by X-ray photoelectron spectroscopy which also gave information on respective oxidation states of cations. Several modes of vibration due to metal-oxygen bonds of pyrochlore-like material were studied by Fourier-transform infrared spectroscopy. The results suggested that this compound contained major component of pyrochlore and minor component of CeO2. The dielectric measurements carried out at frequency 1 MHz in temperature range –40°C–90°C proved that pyrochlore compound possessed dielectric constants ranging between 12 and 28. Furthermore, owing to its high electrical conductivity, synthesised material has been utilised as bioanode in a microbial fuel cell. This bio-electrochemical device converted organic wastes into electricity using microorganisms as biocatalysts. It displayed greater electron transfer from electroactive biofilm towards the bioanode by improving its electrical energy output. The presence of pyrochlore in electrode allowed a power density of 25 mW/m2. It was almost the same as that obtained with a graphite carbon modified by the conducting polymer polypyrrole. The MFC with pyrochlore solid oxide was advantageously more stable having longer lifetime and indicating its suitability to substitute the polypyrrole at the bioanode. Besides, the colour of the coffee mac leachate in the anolyte (anode compartment) became less dark, which means that the maximum chemical oxygen demand (COD) was removed and converted into electric energy. [ABSTRACT FROM AUTHOR]

Composites of sodium-exchanged zeolite chabazite particles with attached superparamagnetic nanoparticles of Fe3O4 and CoFe2O4 ferrite spinels have been produced using a novel solvothermal route. These have been characterized by a combination of techniques, including powder x-ray diffraction, x-ray fluorescence spectroscopy, vibrating sample magnetometry, and both scanning and transmission electron microscopy. These confirm the nature of the attached nanoparticles, and the microscope images show a good dispersion of nanoparticles with a narrow size range deposited uniformly on the surface of the zeolite particles. The magnetization is of sufficient strength to allow magnetic separation from a solution. Both time and pH dependent Cs uptake experiments show that the magnetized systems are still excellent for the rapid uptake of Cs via an ion exchange process with no reduction in property due to the attached nanoparticles. [ABSTRACT FROM AUTHOR]

A facile and original approach based on a one-pot non-aqueous sol–gel solvothermal process was developed to synthesize 2D Tungsten trioxide (WO3) nanoplatelets with an average size ranging from 30 to 50 nm, and a correspondingly high surface area. The structural, morphological, functional group, optical properties of the materials, and the properties of the adsorption surfaces were all investigated; the degree of surface hydroxyls (–OH groups) has been examined. Nuclear Magnetic Resonance Spectroscopy techniques indicated the formation of di-hexyl ether as a result of the solvothermal reaction. The optical absorption, measured using UV–Vis Diffuse Reflectance Spectroscopy, revealed a narrow bandgap (Eg = 2.18 and 2.48 eV for WO3-24 and WO3-48, respectively) compared to that of for bulk WO3 (2.7 eV), attributable to oxygen vacancies. The as-prepared WO3 nanoplatelets displayed excellent photocatalytic performance for degrading Rhodamine B under visible light-emitting diode light with up 99% degradation rate that was achieved in 120 min. Thus, the enhanced Rhodamine B photodegradation in the presence of WO3-24 along with H2O2 was assigned to the reactive oxygen species such as ·OH and RhB*+, involving in the strong synergistic effect between WO3 and H2O2, effectively separating of photocarriers and, as a consequence, boosting the photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4), possessing high thermal and chemical stability, non-toxicity, facile synthesis, and low band gap energy is a promising candidate for photocatalytic applications. In this study, bulk and exfoliated g-C3N4 were synthesised from different precursors (melamine and urea). Moreover, the surface of bulk g-C3N4 and exfoliated g-C3N4 was modified with graphene (0.5 wt% and 1 wt%) aiming to obtain a prolonged carrier lifetime. The effect of g-C3N4 synthesis from various precursors and the influence of graphene content on the photocatalytic activity during the degradation of a water–methanol mixture under UVC irradiation were examined, in comparison to commercial P25. Hydrogen, methane and carbon monoxide were the decomposition products; hydrogen was the main product of decomposition, whereas CH4 and CO resulting from the reduction of CO2 were generated in a significantly smaller amount. All the produced photocatalysts, whether pure or modified with graphene, exhibited higher activity than the commercial photocatalyst P25. [ABSTRACT FROM AUTHOR]

We applied a general non-aqueous route for the formation of mono-, bi-, tri-, tetra, hexapod and multipod magnetic spinel ferrite metal oxide (CoFe2O4) nanocrystals. The magnetic CoFe2O4 nanocrystals were characterized by X-ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy, magnetometry and Mössbauer spectroscopy, to understand their structure and magnetic properties. These CoFe2O4 nanoparticles have the smallest particle size reported ever, with a mean diameter of ∼3 nm. The coercivity was found to be larger compared to that reported in the literature for spherical particles. Mössbauer spectroscopy indicated a magnetic transition above room temperature, where 20% of the Fe ions transit to a paramagnetic state, around 400 K. From the thermal dependence of magnetic parameters, the blocking temperature was estimated to be around 425 K. These studies indicate that our CoFe2O4 nanocrystals are different from their cubic/spherical counterparts, which generally display a single domain character. These CoFe2O4 nanocrystals display a strong shape anisotropy dependent magnetic property. [ABSTRACT FROM AUTHOR]

The porous metal–organic framework UiO-66(Zr) obtained via non modulated synthesis, has revealed to be a notable heterogeneous catalyst, enabling extremely fast and very efficient desulfurization of a multicomponent model diesel and also a real diesel fuel. [ABSTRACT FROM AUTHOR]

In this article, the versatility and the potential of the 'benzyl alcohol route' for the synthesis of multimetal and doped metal oxides are highlighted in the first part of the manuscript. Among the presented examples, some materials have not been accessible by other solution syntheses and could so far only be obtained through solid state reactions. The second part describes the synthesis and characterization of 5-6 nm ZnAlO nanoparticles which form flower-like aggregates through the oriented attachment crystallization mechanism. [ABSTRACT FROM AUTHOR]