Redox Properties of Ordered Macroporous Ce–Zr Mixed Oxides

Abstract

Chlorine-free, finely textured three-dimensionally ordered macroporous mixed oxides of nominal composition Zr 0.6 Ce 0.4 O 2 were prepared by the opal template technique. Electron microscopy showed a well-defined porosity that can be controlled with the infiltration process. By using thermal analysis and X-ray photoelectron spectroscopy ͑XPS͒, the oxygen storage and the redox response to different environments have been investigated. Multiple high temperature oxidation-reduction cycles decrease the initial high sensitivity of the surface oxidation state of Ce to the environment ͑aging processes͒. This has been ascribed to the development of Ce͑III͒-rich phases. Analysis of X-ray diffraction, energy-dispersive X-ray spectroscopy, and photoemission data indicated the coexistence of a Zr-rich and a Ce-rich phase. In XPS, we observe binding energy shifts in consequence of the redox treatments and explain them as shifts of the Fermi level linked to variations in the Ce oxidation state.

Surface study of cerium oxide based coatings obtained by cathodic electrodeposition on zinc

“…3a presents the analysis of the Ce 3d core level spectra. Details of the analysis procedure are given elsewhere [18]. The shadowed components (blue) corresponded to Ce (III) and the empty ones (red) to Ce (IV).…”

Aspect-ratio and lateral-resolution enhancement in force microscopy by attaching nanoclusters generated by an ion cluster source at the end of a silicon tip

“…Finally, we have also recorded AFM images on a two-dimensional system made of ordered macroporous Ce-Zr mixed oxides 33,34 that display an hexagonal array. The corresponding images are displayed in Fig.…”

“…In our case we have measured the following systems: (1) submonolayer of 10 nm diameter Co 95 Au 5 clusters deposited on a flat silicon wafer surface, (2) single wall carbon nanotubes deposited on a flat silicon wafer, 32 and (3) ordered macroporous Ce-Zr mixed oxides. 33,34 The images were taken at a scanning rate of 1 Hz, with a pixel resolution of 512 × 512 in the X and Y axes and 1 μm × 1 μm scanning size. In some cases, a zoom of the desired area has been taken from the original picture in order to get a clearer view of the region of interest.…”