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The industrial fluorination of UO2 to UF4 is based on a complex process involving the manipulation of a large amount of HF, a very toxic and corrosive gas. We present here a safer way to accomplish this reaction utilizing ionic liquid [Bmim][PF6] as a unique reaction medium and fluoride source. [ABSTRACT FROM AUTHOR]

The industrial fluorination of UO2 to UF4 is based on a complex process involving the manipulation of a large amount of HF, a very toxic and corrosive gas. We present here a safer way to accomplish this reaction utilizing ionic liquid [Bmim][PF6] as a unique reaction medium and fluoride source. [ABSTRACT FROM AUTHOR]

BaNiO3 crystal to BaNiO2 crystal transformation is reported. Contrary to an intuitive topochemical reduction, a two step reaction was observed. In the first step, NiO exsolution occurs and intermediate Ba1+xNiO3 phases were obtained and isolated. A composite approach was used to solve the novel structure for x∼ 1/6 with charge ordered Ni2+ and Ni4+. We argue that this NiO exsolution is responsible for the increased oxygen enhanced reactivity recently reported. Upon re-oxidation, oxygen-deficient mixed valent BaNi3/4+O3−x are obtained such that the full redox cycle is irreversible and goes through a diversity of structural and nickel valence adaptative oxides. [ABSTRACT FROM AUTHOR]

Lanthanum orthoferrite, a highly potential 3‐way catalyst, shaped as a polycrystalline thin film has been comprehensively analysed by combining bulk and surface characterization techniques. The possibility to accomplish unprecedented surface information has been presented, thanks to the combined use of LEIS, XPS, and ToF‐SIMS. The structural, morphological, and surface properties at nanometric scale make such thin films indistinguishable from powdered solids. Thus, the relevance of using such model materials for advanced surface investigations of LaFeO3±δ‐based 3‐way catalysts has been demonstrated. [ABSTRACT FROM AUTHOR]

A ZnFe2O4/γ-Fe2O3 nanocomposite (theoretical specific capacity: 1002 mA h g−1) was successfully synthesized by laser pyrolysis, a very attractive nanosynthesis technique characterized by high versatility and flexibility. The obtained nanopowder was thoroughly characterized by XRD, XPS, Mössbauer spectroscopy and HRTEM, which confirmed the presence of two phases. A bimodal size distribution with small particles (tens of nanometers) and large ones (above 500 nm) was revealed by SEM and TEM. The ZnFe2O4/Fe2O3 nanocomposite was tested as a negative electrode material for lithium-ion batteries, showing significantly improved lithium storage properties with a high reversible capacity and rate capability compared to a pure ZnFe2O4 electrode. A capacity exceeding 1200 mA h g−1 is sustained after 100 cycles at 100 mA g−1, with a gradual increase of the capacity during cycling. At 500 mA g−1 current rate, a reversible and stable capacity of 360 mA h g−1 is observed after 300 cycles. Electrochemical measurements with several electrolytes and electrode formulations were also conducted in order to explore the origin of the extra capacity and its increase with cycling. [ABSTRACT FROM AUTHOR]

In this study, the characterization of nanostructured Pt-doped CeO2 films with low platinum content and porous structure is reported, deposited on silicon substrate by direct liquid injection chemical vapor deposition. The platinum localization and concentration in the nanocomposite are determined by scanning transmission electron microscopy associated with energy dispersive X-ray spectroscopy. Films are made of ≈3 nm diameter CeO2 particles and platinum is homogeneously dispersed through the layers. X-ray photoelectron spectroscopy (XPS) also shows that platinum is mainly in an ionic Pt2+ state. After diffusion through the preformed porous structure of ceria films, the platinum precursor decomposes at the surface of each ceria particle forming the films, producing a homogeneous platinum-doped CeO2 nanocomposite. This result is supported by synchrotron radiation XPS experiment, where the measured relative Pt concentration demonstrates that platinum is decomposed only at the surface of ceria particles. Finally, when the saturation of Pt2+ sites at the surface of ceria particles is reached, metallic nanoclusters are formed from platinum excess. [ABSTRACT FROM AUTHOR]

Among semiconductor nanomaterials, titanium dioxide is at the forefront of heterogeneous photocatalysis, but its catalytic activity greatly suffers from the loss of photoexcited charge carriers through deleterious recombination processes. Here, we investigate the impact of an external electric field (EEF) applied to conventional P25 TiO 2 nanopowder with or without Au nanoparticles (NPs) to circumvent this issue. The study of two redox reactions in the gas phase, water splitting and toluene degradation, reveals an enhancement of the photocatalytic activity with rather modest electric fields of a few volt/centimeters only. Such an improvement arises from the electric-field-induced quenching of the green emission in anatase, allowing the photoexcited charge carriers to be transferred to the adsorbed reactants instead of pointless radiative recombinations. Applying an EEF across a trap-rich metal oxide material, such as TiO 2 , which, when impregnated with Au NPs, leads, respectively, to 12- and 6-fold enhancements in the production of hydrogen and the oxidation of toluene for an electric field of 8 V/cm, without any electrolysis, is a simple and elegant strategy to meet higher photocatalytic efficiencies.

The mixed-valent iron arsenate hydroxide Fe 13.5 2.22+ (AsO 4- x ) 8 (OH) 6 , x = 0.25, was prepared using the reaction of iron metal with arsenate in aqueous solution and autogenous pressure. Its crystal structure reveals a dumortierite-like framework with mixed-valent Fe 2+/ Fe 3+ in double chains creating channel walls. Remarkably, hexagonal channels consist of chains of face-sharing Fe 2+ O 6 octahedra, 3/4th occupied, whereas AsO 4 tetrahedra occupy triangular ones with a single " up" orientation according to the polar P6 3 mc symmetry. We have analyzed the transformation of this phase upon heating, in which several chemical processes interact, including dehydroxylation, arsenate to arsenite reduction, and oxidative exsolution of a significant part of iron (ca. 15%) found at the surface as hematite and amorphous Fe-rich surficial layer. It leaves a strongly disordered composite structure between several Fe 3+ -based subunits, in which ∼80% of them is ordered in a complex supercell. Because of the high degree of disorder, the crystal chemistry of the individual subunits and their plausible imbrication were considered to unravel the most plausible ideal 3D model.