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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]

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]

Because of its electrically conducting properties combined with excellent thermal stability and transparency throughout the visible spectrum, tin oxide (SnO 2 ) is extremely attractive as a transparent conducting material for applications in low-emission window coatings and solar cells, as well as in lithium-ion batteries and gas sensors. It is also an important catalyst and catalyst support for oxidation reactions. Here, we describe a novel nonaqueous sol-gel synthesis approach to produce tin oxide nanoparticles (NPs) with a low NP size dispersion. The success of this method lies in the nonhydrolytic pathway that involves the reaction between tin chloride and an oxygen donor, 1-hexanol, without the need for a surfactant or subsequent thermal treatment. This one-pot procedure is carried out at relatively low temperatures in the 160-260 °C range, compatible with coating processes on flexible plastic supports. The NP size distribution, shape, and dislocation density were studied by powder X-ray powder diffraction analyzed using the method of whole powder pattern modeling, as well as high-resolution transmission electron microscopy. The SnO 2 NPs were determined to have particle sizes between 3.4 and 7.7 nm. The reaction products were characterized using liquid-state 13 C and 1 H nuclear magnetic resonance (NMR) that confirmed the formation of dihexyl ether and 1-chlorohexane. The NPs were studied by a combination of 13 C, 1 H, and 119 Sn solid-state NMR as well as Fourier transform infrared (FTIR) and Raman spectroscopy. The 13 C SSNMR, FTIR, and Raman data showed the presence of organic species derived from the 1-hexanol reactant remaining within the samples. The optical absorption, studied using UV-visible spectroscopy, indicated that the band gap ( E g ) shifted systematically to lower energy with decreasing NP sizes. This unusual result could be due to mechanical strains present within the smallest NPs perhaps associated with the organic ligands decorating the NP surface. As the size increased, we observed a correlation with an increased density of screw dislocations present within the NPs that could indicate relaxation of the stress. We suggest that this could provide a useful method for band gap control within SnO 2 NPs in the absence of chemical dopants., Competing Interests: The authors declare no competing financial interest.

We present for the first time a nonaqueous sol-gel route to produce ultrasmall (<2 nm) magnetic bimetallic CoPt 3 nanoparticles (NPs). The one-pot procedure is carried out at low temperature (180 °C) using benzyl alcohol, acting as both reducing agent and solvent. The highly monodisperse CoPt 3 NPs were investigated with innovative advanced X-ray methods (whole powder pattern modeling), HR-STEM, XPS, and SQUID magnetometry. XPS showed Co was mostly in metallic form, but with a very small amount of CoO on the NP surface. The spherical NPs had an ultrasmall diameter of 1.6 nm and could self-assemble in aligned linear chains, or nanobelts, of single NPs. They are superparamagnetic, with blocking temperature of ∼20 K and coercivity at 10 K of 27.9 kA m -1 (∼350 Oe). However, there is evidence of a second magnetic phase (probably CoO) in the ZFC magnetization curve, which enhances their magnetization values, without significantly affecting their superparamagnetism.