Redox behavior of thermally aged ceria-zirconia mixed oxides. Role of their surface and bulk structural properties. Yeste, M., Hernández-Garrido, J., Bernal, S., Blanco, G., Calvino, J., Pérez-Omil, J., & Pintado, J. Chemistry of Materials, 18(11):2750–2757, Departamento de Ciencia de Los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Campus Río San Pedro, E-11510 Puerto Real (Cádiz), Spain, 2006.
Redox behavior of thermally aged ceria-zirconia mixed oxides. Role of their surface and bulk structural properties [link]Paper  abstract   bibtex   
The relationship existing between aging conditions, redox behavior, and surface/bulk structural properties of two thermally aged ceria-zirconia mixed oxides, CZ-MO and CZ-SO, is analyzed. The samples were prepared by applying to a fresh Ce0.62Zr0.38O2 mixed oxide two alternative aging routines consisting of a reduction with H2 at 1223 K (5 h), followed by either a mild, CZ-MO, or severe, CZ-SO, re-oxidation treatment. By combining high-resolution electron microscopy and a number of chemical charcterization techniques, it is shown that the nanostructure of the aged oxides, specifically the total amount and surface presence of the phase exhibiting an ordered cationic sublattice ($ąppa$-like phase), is a key factor in determining their redox response. In the low-temperature reduction range (Tredn ≤ 773 K), the enhanced reducibility of the CZ-MO sample is proposed to be kinetically controlled by its surface structure mainly consisting of the $ąppa$-like phase. In accordance with the reported results, the surface activation of the H2 molecule, much faster on the CZ-MO sample, is proposed to be the rate controlling step of the overall reduction process. This proposal was further confirmed by the dramatic downward shift observed in the temperature-programmed reduction diagrams recorded for the corresponding oxide-supported rhodium samples. By contrast, in the high-temperature reduction range (Tredn ≥ 973 K), the observed difference of reducibility, higher in the case of the CZ-MO sample, is interpreted as due to thermodynamic factors related to the nature of the predominant cationic sublattice structure, ordered for CZ-MO and disordered in the case of the CZ-SO sample. © 2006 American Chemical Society.
@article{Yeste2006,
abstract = {The relationship existing between aging conditions, redox behavior, and surface/bulk structural properties of two thermally aged ceria-zirconia mixed oxides, CZ-MO and CZ-SO, is analyzed. The samples were prepared by applying to a fresh Ce0.62Zr0.38O2 mixed oxide two alternative aging routines consisting of a reduction with H2 at 1223 K (5 h), followed by either a mild, CZ-MO, or severe, CZ-SO, re-oxidation treatment. By combining high-resolution electron microscopy and a number of chemical charcterization techniques, it is shown that the nanostructure of the aged oxides, specifically the total amount and surface presence of the phase exhibiting an ordered cationic sublattice ($\kappa$-like phase), is a key factor in determining their redox response. In the low-temperature reduction range (Tredn ≤ 773 K), the enhanced reducibility of the CZ-MO sample is proposed to be kinetically controlled by its surface structure mainly consisting of the $\kappa$-like phase. In accordance with the reported results, the surface activation of the H2 molecule, much faster on the CZ-MO sample, is proposed to be the rate controlling step of the overall reduction process. This proposal was further confirmed by the dramatic downward shift observed in the temperature-programmed reduction diagrams recorded for the corresponding oxide-supported rhodium samples. By contrast, in the high-temperature reduction range (Tredn ≥ 973 K), the observed difference of reducibility, higher in the case of the CZ-MO sample, is interpreted as due to thermodynamic factors related to the nature of the predominant cationic sublattice structure, ordered for CZ-MO and disordered in the case of the CZ-SO sample. © 2006 American Chemical Society.},
address = {Departamento de Ciencia de Los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Campus R\'{\i}o San Pedro, E-11510 Puerto Real (C\'{a}diz), Spain},
annote = {Cited By (since 1996): 34

        
Export Date: 15 January 2013

        
Source: Scopus

        
CODEN: CMATE

        
doi: 10.1021/cm060635i

        
Language of Original Document: English

        
Correspondence Address: Bernal, S.; Departamento de Ciencia de Los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Facultad de Ciencias, Campus R\'{\i}o San Pedro, E-11510 Puerto Real (C\'{a}diz), Spain; email: serafin.bernal@uca.es

        
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author = {Yeste, MP. and Hern\'{a}ndez-Garrido, JC. and Bernal, S. and Blanco, G. and Calvino, JJ. and P\'{e}rez-Omil, JA. and Pintado, JM.},
issn = {08974756 (ISSN)},
journal = {Chemistry of Materials},
keywords = {Aging of materials,Cationic sublattice,Chemical characterization techniques,Electron microscopy,High-resolution electron microscopy,Optical resolving power,Positive ions,Redox reactions,Structural properties,Surface properties,Thermal effects,Thermoanalysis,Zirconia},
number = {11},
pages = {2750--2757},
title = {{Redox behavior of thermally aged ceria-zirconia mixed oxides. Role of their surface and bulk structural properties}},
url = {https://www.scopus.com/inward/record.url?eid=2-s2.0-33744974809&partnerID=40&md5=4b52f1e79118f084a4e375b8e5de4675},
volume = {18},
year = {2006}
}
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