Identification of the Structural Phases of Ce_xZr_1−xO₂ by Eu(III) Luminescence Studies

Abstract

Despite the wide application of ceria-zirconia based materials in Three Way Catalysts (TWCs), Solid Oxides Fuel Cells (SOFCs), and H(2) production and purification reactions, an active debate is still open on the correlation between their structure and redox/catalytic performances. Existing reports support the need of either (i) a homogeneous solid solution or (ii) materials with nanoscale heterogeneity to obtain high activity and stability. Here we report on a simple and inexpensive approach to solve this problem taking advantage of the luminescence properties of Eu(III), used as a structural probe introduced either in the bulk or on the surface of the samples. In this way, the real structure of ceria-zirconia materials can be revealed even for amorphous high surface area samples. Formation of small domains is observed in catalytically important metastable samples which appear homogeneous by conventional XRD.

Synthesis of CeO2–ZrO2 solid solution by glycothermal method and its oxygen release capacity

“…When re-oxidation of a reduced Ce 0.5 Zr 0.5 O 2 sample was carried out at 700 K, subsequent reduction occurred at lower temperature than the antecedent reduction, while re-oxidation at high temperature (1273K) restored the high temperature reduction peak. Although their textual properties associated with the structural modifications occurring in the bulk or surface are assumed to be the factors [35], details of the behavior of Homogeneity of CeO 2 -ZrO 2 solid solutions is a crucial factor to increase their OSC capacity, although the presence of nanodomains of Ce-rich and Zr-rich phases that cannot be detected by conventional diffraction analysis [48,49] in apparently homogeneous sample cannot be ruled out.…”

Chemoselective Hydrogenation of Cinnamaldehyde over Pd/CeO2–ZrO2 Catalysts

“…At intermediate compositions, various phases (t, t 0 , t 00 , j and t*) have been identified [22][23][24]. Oxygen deficient structures, such as the pyrochlore structure (A 2 B 2 X 7 ) may also be formed [25][26][27][28][29]. For ceria-zirconia mixed oxides, the pyrochloric structure is generally reported to be formed under severe reduction conditions.…”

A new insight into the effects of barium addition on Pd-only catalysts: Pd-support interface and CO+NO reaction pathway

“…The main diffraction peaks of all the samples are consistent with the characteristic peaks of Ce 0.5 Zr 0.5 O 2 (PDF#38-1436), which is identified to be the t (P4 2 nmc) phase [29]. The barium addition in CZ support seems to be no use for suppressing the sintering of CZ.…”