Sulfidation Mechanism of Pure and Cu-Doped ZnO Nanoparticles at Moderate Temperature: TEM and In Situ XRD Studies
International audience; Sulfidation mechanism of pure and Cu-doped ZnO nanoparticles (Cu0.03Zn0.97O and Cu0.06Zn0.94O) at 250 and 350 degrees C was studied by transmission electron microscopy (TEM) and in situ synchrotron XRD. For nondoped ZnO, we observed by TEM that partial reaction with H2S is accompanied by the formation of voids at the ZnO/ZnS interface. This phenomenon (known as the Kirkendall effect) confirms that sulfidation of nanosized ZnO by gaseous H2S proceeds via the outward growth of ZnS: Zn2+ and O2- are transferred to the external (ZnS/gas) surface, where zinc is combined with sulfur and oxygen reacts with protons yielding H2O. During sulfidation of Cu-doped ZnO, the caviti…
2.8NiO–H1.8Ni0.6(OH)MoO4—Novel nanocomposite material for the reactive adsorption of sulfur-containing molecules at moderate temperature
Abstract It has been found that a poorly crystalline green precipitate that forms in boiling ammonia solution of Ni(NO 3 ) 2 and (NH 4 ) 6 Mo 7 O 24 yields on annealing a Ni-rich material (Ni/Mo = 3.4) containing slit shaped mesopores and exhibiting the BET surface area of 230 m 2 /g. Characterization of the material by TGA, XRD, TEM, SEM, and EXAFS allowed to determine that it is a nanocomposite consisting of Ni–Mo (hydro)oxide layers H 1.8 Ni 0.6 (OH)MoO 4 which are pillared by NiO nanoparticles ( D = 3 nm). The structure of the layers appears to be similar to that found in the previously described crystalline molybdate (NH 4 )HNi 2 (OH) 2 (MoO 4 ) 2 prepared in the similar conditions. T…
Pd2Au36(SR)(24) cluster: structure studies
The location of the Pd atoms in Pd2Au36(SC2H4Ph)(24), is studied both experimentally and theoretically. X-ray photoelectron spectroscopy (XPS) indicates oxidized Pd atoms. Palladium K-edge extended X-ray absorption fine-structure (EXAFS) data clearly show Pd-S bonds, which is supported by far infrared spectroscopy and by comparing theoretical EXAFS spectra in R space and circular dichroism spectra of the staple, surface and core doped structures with experimental spectra.