Redox Properties of Nanocrystalline Cu-Doped Cerium Oxide Studied by Isothermal Gravimetric Analysis and X-ray Photoelectron Spectroscopy

Andreas Tschöpe; Michel L. Trudeau; Jackie Y. Ying

doi:10.1021/jp9915681

Redox Properties of Nanocrystalline Cu-Doped Cerium Oxide Studied by Isothermal Gravimetric Analysis and X-ray Photoelectron Spectroscopy

Andreas Tschöpe^*, Michel L. Trudeau, Jackie Y. Ying

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

55 Scopus citations

Abstract

Nanostructured CeO_2-x and Cu_0.15Ce_0.85O_2-x were synthesized by high-pressure magnetron sputtering. X-ray diffraction was used for phase analysis and grain size characterization. The structural analysis indicated that Cu was highly dispersed, which could be explained by surface segregation on cerium oxide nanocrystals. The reduction and oxidation of dispersed copper in nanostructured Cu_0.15Ce_0.85O_2-x was investigated by isothermal gravimetric analysis (IGA) and X-ray photoelectron spectroscopy (XPS). In IGA, the sample weight was measured at constant temperature during in situ reduction and oxidation in 2% CO/He or 5% H₂/He and 15% O₂/He, respectively. The weight changes of microcrystalline CeO₂ and nanocrystalline CeO_2-x and Cu_0.15Ce_0.85O_2-x samples were measured at temperatures between 200 and 500 °C. The analysis revealed that more than one oxygen atom was extracted per Cu atom in Cu_0.15Ce_0.85O_2-x during reduction, which was reversibly restored during oxidation. The Cu valence state in Cu_0.15Ce_0.85O_2-x after oxidation or reduction was independently determined by XPS. The Cu 2p core-level spectra and LMM Auger spectra of Cu_0.15Ce_0.85O_2-x were compared with those of a polycrystalline copper reference. The analysis showed that all three oxidation states of copper (i.e., 0, 1+, and 2+) could be present depending on the reduction/oxidation specifications. Furthermore, Cu⁰ and Cu¹⁺ were found to coexist in a stable state under certain conditions.

Original language	English
Pages (from-to)	8858-8863
Number of pages	6
Journal	Journal of Physical Chemistry B
Volume	103
Issue number	42
DOIs	https://doi.org/10.1021/jp9915681
State	Published - 21 Oct 1999
Externally published	Yes

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Surfaces, Coatings and Films
Materials Chemistry

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@article{144d753d91cc4a5e8d7e50abac33b90c,

title = "Redox Properties of Nanocrystalline Cu-Doped Cerium Oxide Studied by Isothermal Gravimetric Analysis and X-ray Photoelectron Spectroscopy",

abstract = "Nanostructured CeO2-x and Cu0.15Ce0.85O2-x were synthesized by high-pressure magnetron sputtering. X-ray diffraction was used for phase analysis and grain size characterization. The structural analysis indicated that Cu was highly dispersed, which could be explained by surface segregation on cerium oxide nanocrystals. The reduction and oxidation of dispersed copper in nanostructured Cu0.15Ce0.85O2-x was investigated by isothermal gravimetric analysis (IGA) and X-ray photoelectron spectroscopy (XPS). In IGA, the sample weight was measured at constant temperature during in situ reduction and oxidation in 2\% CO/He or 5\% H2/He and 15\% O2/He, respectively. The weight changes of microcrystalline CeO2 and nanocrystalline CeO2-x and Cu0.15Ce0.85O2-x samples were measured at temperatures between 200 and 500 °C. The analysis revealed that more than one oxygen atom was extracted per Cu atom in Cu0.15Ce0.85O2-x during reduction, which was reversibly restored during oxidation. The Cu valence state in Cu0.15Ce0.85O2-x after oxidation or reduction was independently determined by XPS. The Cu 2p core-level spectra and LMM Auger spectra of Cu0.15Ce0.85O2-x were compared with those of a polycrystalline copper reference. The analysis showed that all three oxidation states of copper (i.e., 0, 1+, and 2+) could be present depending on the reduction/oxidation specifications. Furthermore, Cu0 and Cu1+ were found to coexist in a stable state under certain conditions.",

author = "Andreas Tsch{\"o}pe and Trudeau, \{Michel L.\} and Ying, \{Jackie Y.\}",

year = "1999",

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T1 - Redox Properties of Nanocrystalline Cu-Doped Cerium Oxide Studied by Isothermal Gravimetric Analysis and X-ray Photoelectron Spectroscopy

AU - Tschöpe, Andreas

AU - Trudeau, Michel L.

AU - Ying, Jackie Y.

PY - 1999/10/21

Y1 - 1999/10/21

N2 - Nanostructured CeO2-x and Cu0.15Ce0.85O2-x were synthesized by high-pressure magnetron sputtering. X-ray diffraction was used for phase analysis and grain size characterization. The structural analysis indicated that Cu was highly dispersed, which could be explained by surface segregation on cerium oxide nanocrystals. The reduction and oxidation of dispersed copper in nanostructured Cu0.15Ce0.85O2-x was investigated by isothermal gravimetric analysis (IGA) and X-ray photoelectron spectroscopy (XPS). In IGA, the sample weight was measured at constant temperature during in situ reduction and oxidation in 2% CO/He or 5% H2/He and 15% O2/He, respectively. The weight changes of microcrystalline CeO2 and nanocrystalline CeO2-x and Cu0.15Ce0.85O2-x samples were measured at temperatures between 200 and 500 °C. The analysis revealed that more than one oxygen atom was extracted per Cu atom in Cu0.15Ce0.85O2-x during reduction, which was reversibly restored during oxidation. The Cu valence state in Cu0.15Ce0.85O2-x after oxidation or reduction was independently determined by XPS. The Cu 2p core-level spectra and LMM Auger spectra of Cu0.15Ce0.85O2-x were compared with those of a polycrystalline copper reference. The analysis showed that all three oxidation states of copper (i.e., 0, 1+, and 2+) could be present depending on the reduction/oxidation specifications. Furthermore, Cu0 and Cu1+ were found to coexist in a stable state under certain conditions.

AB - Nanostructured CeO2-x and Cu0.15Ce0.85O2-x were synthesized by high-pressure magnetron sputtering. X-ray diffraction was used for phase analysis and grain size characterization. The structural analysis indicated that Cu was highly dispersed, which could be explained by surface segregation on cerium oxide nanocrystals. The reduction and oxidation of dispersed copper in nanostructured Cu0.15Ce0.85O2-x was investigated by isothermal gravimetric analysis (IGA) and X-ray photoelectron spectroscopy (XPS). In IGA, the sample weight was measured at constant temperature during in situ reduction and oxidation in 2% CO/He or 5% H2/He and 15% O2/He, respectively. The weight changes of microcrystalline CeO2 and nanocrystalline CeO2-x and Cu0.15Ce0.85O2-x samples were measured at temperatures between 200 and 500 °C. The analysis revealed that more than one oxygen atom was extracted per Cu atom in Cu0.15Ce0.85O2-x during reduction, which was reversibly restored during oxidation. The Cu valence state in Cu0.15Ce0.85O2-x after oxidation or reduction was independently determined by XPS. The Cu 2p core-level spectra and LMM Auger spectra of Cu0.15Ce0.85O2-x were compared with those of a polycrystalline copper reference. The analysis showed that all three oxidation states of copper (i.e., 0, 1+, and 2+) could be present depending on the reduction/oxidation specifications. Furthermore, Cu0 and Cu1+ were found to coexist in a stable state under certain conditions.

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DO - 10.1021/jp9915681

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JO - Journal of Physical Chemistry B

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IS - 42

ER -

Redox Properties of Nanocrystalline Cu-Doped Cerium Oxide Studied by Isothermal Gravimetric Analysis and X-ray Photoelectron Spectroscopy

Abstract

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