Specificity of the Local Structure of Nanocrystalline Doped Ceria Solid Electrolytes

Abstract

This work presents results of studies of the structural features of nanocrystalline doped Ce1−xMexO2−y samples (Me = Sm, Bi, Gd; X = 0–0.5) prepared via the polymerised precursor (Pechini) route by using a combination of diffraction (XRD, TEM, WAXS on SR) and spectroscopic (EXAFS, Raman, FTIRS of lattice modes, XPS, SIMS) methods.

Tap study of the impact of the oxidation state of Pt/PrCeZrO and Pt/GdCeZrO catalysts on their reactivity in the partial/deep oxidation of methane

“…Hence, the Gd-doped sample is characterized by the presence of rather weakly bound and, perhaps, highly reactive surface oxygen species. This feature can be assigned to a higher concentration of the surface oxygen vacancies for the Gd-doped ceria-zirconia system [5]. However, apparently more oxygen is desorbed in a TPD run from the Pr-doped sample, especially at high temperatures.…”

“…Complex fluorite-like Me 0.3 Ce 0.35 Zr 0.35 O 2-x oxides (Me = Pr, Gd) were prepared via a modified Pechini route and calcined under air at 500°C for 4 h as described elsewhere [5,11]. The Pt (1.4 wt%) was supported by the incipient wetness impregnation from a H 2 PtCl 6 solution followed by drying and calcination at 500°C for 2 h. Detailed catalyst characterizations using XRD, Raman, O 2 -TPD, and CH 4 -TPR techniques are reported elsewhere [5,10].…”

“…The Pt (1.4 wt%) was supported by the incipient wetness impregnation from a H 2 PtCl 6 solution followed by drying and calcination at 500°C for 2 h. Detailed catalyst characterizations using XRD, Raman, O 2 -TPD, and CH 4 -TPR techniques are reported elsewhere [5,10].…”

“…Pt supported on fluorite-like oxides (doped ceria, ceria-zirconia) was recently shown to possess a good performance in POM at short contact times [4,5]. Preliminary data [4] suggest that the reaction follows the so-called direct route of syngas generation.…”

“…Using small pulses of the reaction mixture, as provided by the temporal analysis of products (TAP) technique [6][7][8][9], enables one to perform these kinds of studies. Doping of ceria-zirconia with Gd or Pr cations, apart from stabilization of this solid solution under high-temperature operation conditions, also allows one to adjust the surface/lattice oxygen mobility and the size/ charge state of Pt clusters on these supports [4,5], which affect the rates and routes of CH 4 transformation.…”