Exploring Reversible Redox Behavior in the 6H-BaFeO (0 < δ < 0.4) System: Impact of Fe/Fe Ratio on CO Oxidation.

This work is devoted to evaluating the relationship between the oxygen content and catalytic activity in the CO oxidation process of the 6H-type BaFeO system. Strong evidence is provided about the improvement of catalytic performance with increasing Fe average oxidation state, thus suggesting the involvement of lattice oxygen in the catalytic process. The compositional and structural changes taking place in both the anionic and cationic sublattices of the catalysts during redox cycles have been determined by temperature-resolved neutron diffraction.

Quantitative, Spectro-kinetic Analysis of Oxygen in Electron-Beam Sensitive, Multimetallic Oxide Nanostructures.

The oxygen stoichiometry of hollandite, KxMnO2-δ, nanorods has been accurately determined from a quantitative analysis of scanning-transmission electron microscopy (STEM) X-Ray Energy Dispersive Spectroscopy (XEDS) experiments carried out in chrono-spectroscopy mode. A methodology combining 3D reconstructions of high-angle annular dark field electron tomography experiments, using compressed-sensing algorithms, and quantification through the so-called ζ-factors method of XEDS spectra recorded on a high-sensitivity detector has been devised to determine the time evolution of the oxygen content of nanostructures of electron-beam sensitive oxides. Kinetic modeling of O-stoichiometry data provided K0.

CO Methanation over NiO-CeO Mixed-Oxide Catalysts Prepared by a Modified Co-Precipitation Method: Effect of the Preparation pH on the Catalytic Performance.

In this study, a series of NiO-CeO mixed-oxide catalysts have been prepared by a modified co-precipitation method similar to the one used for the synthesis of hydrotalcites. The syntheses were carried out at different pH values (8, 9 and 10), in order to determine the influence of this synthetic variable on the properties of the obtained materials. These materials were characterized by using different techniques, such as TGA, XRD, ICP, N adsorption-desorption isotherms, H temperature-programmed reduction (H-TPR), and electron microscopy, including high-angle annular dark-field transmission electron microscopy (HAADF-TEM) and EDS.

Ultrathin Washcoat and Very Low Loading Monolithic Catalyst with Outstanding Activity and Stability in Dry Reforming of Methane.

A Ni/CeO/ZrO catalyst with improved redox properties has been washcoated onto a honeycomb cordierite monolith in the form of a nonconventional alumina-catalyst layer, just a few nanometers thick. In spite of the very low active phase loading, the monolith depicts outstanding performance in dry reforming of methane, both in terms of activity, with values reaching the thermodynamic limit already at 750 °C, even under extreme Weight Hourly Space Velocities (WHSV 115-346 L·g·h), as well as in terms of stability during prolonged Time on Stream (TOS 24-48 h).

Performance of a Direct Methane Solid Oxide Fuel Cell Using Nickel-Ceria-Yttria Stabilized Zirconia as the Anode.

A nickel-ceria-yttria stabilized zirconia (Ni-CYSZ) cermet material was synthesized and tested as the anode for the direct oxidation of methane in a solid oxide fuel cell (SOFC) with YSZ as the electrolyte and strontium-doped lanthanum manganite (LSM) as the cathode. Initially, the electrochemical behavior was investigated under several load demands in wet (3% HO) CH at 850 °C during 144 h using I-V curves, impedance spectra, and potentiostatic measurements. Long-term tests were subsequently conducted under 180 mA·cm in wet CH for 236 h and dry CH for 526 h at 850 °C in order to assess the cell stability.

Catalytic Performance of Ni/CeO/X-ZrO (X = Ca, Y) Catalysts in the Aqueous-Phase Reforming of Methanol.

In this study, we reported on the effect of promoting Ni/ZrO catalysts with Ce, Ca (two different loadings), and Y for the aqueous-phase reforming (APR) of methanol. We mainly focused on the effect of the redox properties of ceria and the basicity provided by calcium or yttrium on the activity and selectivity of Ni in this reaction. A systematic characterization of the catalysts was performed using complementary methods such as XRD, XPS, TPR, CO-TPD, H chemisorption, HAADF-STEM, and EDS-STEM.

Catalytic Soot Oxidation Activity of NiO-CeO Catalysts Prepared by a Coprecipitation Method: Influence of the Preparation pH on the Catalytic Performance.

A series of NiO-CeO mixed oxide catalysts have been synthesized by a modified coprecipitation method at three different pH values (pH = 8, 9, and 10). The NiO-CeO mixed oxide samples were characterized by TGA, XRD, inductively coupled plasma atomic emission spectroscopy (ICP-AES), FTIR, Brunauer-Emmett-Teller (BET) surface area, H temperature-programmed reduction (H-TPR), and electron microscopy (high-angle annular dark-field transmission electron microscopy/energy-dispersive X-ray spectroscopy (HAADF-TEM/EDS)). The catalytic activities of the samples for soot oxidation were investigated under loose and tight contact conditions.

Dramatic effect of redox pre-treatments on the CO oxidation activity of Au/Ce(0.50)Tb(0.12)Zr(0.38)O(2-x) catalysts prepared by deposition-precipitation with urea: a nano-analytical and nano-structural study.

Nano-structural and nano-analytical studies show that the dramatic difference in CO oxidation activity observed between two Au/Ce0.50Tb0.12Zr0.

Role of physicochemical characteristics in the uptake of TiO2 nanoparticles by fibroblasts.

The relation between the physico-chemical properties of nanoparticles (NPs) and the degree of cellular uptake is incompletely elucidated. In this study, we investigated the influence on the cellular uptake of a wide range of fully characterized TiO2 NPs. L929 fibroblasts were exposed for 24 h to clinically relevant concentrations of nano-TiO2 and the degree of their association was assessed by ultrahigh resolution imaging microscopy (URI), scanning (SEM) and transmission (TEM) electron microscopy, as well as inductivity coupled plasma-mass spectroscopy (ICP-MS).

In situ transmission electron microscopy investigation of Ce(IV) and Pr(IV) reducibility in a Rh (1%)/Ce0.8Pr0.2O(2-x) catalyst.

In-situ Atomic Resolution Transmission Electron Microscopy studies carried out on a Rh/Ce0.8Pr0.2O(2-x) catalyst, under hydrogen in the temperature range 298-1223 K, show the occurrence of consecutive reduction of Pr4+ and Ce4+ ions, and the formation of an oxygen-deficient Ln16O30 (Ln: Ce, Pr) ordered phase.