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Title: The interaction of Rh with intrinsic defects of reduced Rh/CeO{sub 2} catalysts: A comparative XPS/UPS and {sup 1}H-NMR study

Abstract

X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) as well as {sup 1}H nuclear magnetic resonance ({sup 1}H-NMR) experiments are reported on Rh surface-doped CeO{sub 2} (111)-oriented thin films and powder samples that are reduced with H{sub 2} at temperatures between 293 and 873 K. Two reduction processes at T {le} 573 K and T > 573 K are found which lead to two distinguishable states of the surface. These temperature regimes are denoted here as low temperature reduction (ltr) and high temperature reduction (Itr). In the ltr-regime the surfaces become hydroxylated and Ce{sup 3+} ions are formed as concluded from XPS. Correspondingly two{sup 1}H-NMR signals of hydrogen that is chemisorbed on Rh and on CeO{sub 2} are detected. In the htr-regime, CeO{sub 2-x} surfaces are by far less hydroxylated, which results from the desorption of H{sub 2}O and the formation oxygen vacancies. Simultaneously, Rh loses its hydrogen adsorption capability, whereas this property is practically constant in the ltr-regime. These findings are correlated to UPS measurements that give evidence for an electronic charge transfer from the CeO{sub 2-x} surface to Rh atoms. Finally this effect is interpreted in terms of the interaction between Rh atoms and oxygen vacancies at themore » CeO{sub 2-x} surface.« less

Authors:
; ;  [1]
  1. Universitaet Tuebingen (Germany); and others
Publication Date:
OSTI Identifier:
468024
Report Number(s):
CONF-960652-
TRN: 96:004817-0061
Resource Type:
Conference
Resource Relation:
Conference: 11. international congress on catalysis (ICC-11), Baltimore, MD (United States), 30 Jun - 5 Jul 1996; Other Information: PBD: 1996; Related Information: Is Part Of 11th International congress on catalysis - 40th anniversary. Part A and B; Hightower, J.W.; Delgass, W.N.; Iglesia, E.; Bell, A.T. [eds.]; PB: 1482 p.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 66 PHYSICS; CERIUM OXIDES; SPECTRA; CATALYTIC EFFECTS; RHODIUM; HYDROGEN 1; NMR SPECTRA; SURFACE AREA; THIN FILMS; X-RAY SPECTRA; ULTRAVIOLET SPECTRA; VACANCIES

Citation Formats

Pfau, A, Schierbaum, K D, and Goepel, W. The interaction of Rh with intrinsic defects of reduced Rh/CeO{sub 2} catalysts: A comparative XPS/UPS and {sup 1}H-NMR study. United States: N. p., 1996. Web.
Pfau, A, Schierbaum, K D, & Goepel, W. The interaction of Rh with intrinsic defects of reduced Rh/CeO{sub 2} catalysts: A comparative XPS/UPS and {sup 1}H-NMR study. United States.
Pfau, A, Schierbaum, K D, and Goepel, W. 1996. "The interaction of Rh with intrinsic defects of reduced Rh/CeO{sub 2} catalysts: A comparative XPS/UPS and {sup 1}H-NMR study". United States.
@article{osti_468024,
title = {The interaction of Rh with intrinsic defects of reduced Rh/CeO{sub 2} catalysts: A comparative XPS/UPS and {sup 1}H-NMR study},
author = {Pfau, A and Schierbaum, K D and Goepel, W},
abstractNote = {X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) as well as {sup 1}H nuclear magnetic resonance ({sup 1}H-NMR) experiments are reported on Rh surface-doped CeO{sub 2} (111)-oriented thin films and powder samples that are reduced with H{sub 2} at temperatures between 293 and 873 K. Two reduction processes at T {le} 573 K and T > 573 K are found which lead to two distinguishable states of the surface. These temperature regimes are denoted here as low temperature reduction (ltr) and high temperature reduction (Itr). In the ltr-regime the surfaces become hydroxylated and Ce{sup 3+} ions are formed as concluded from XPS. Correspondingly two{sup 1}H-NMR signals of hydrogen that is chemisorbed on Rh and on CeO{sub 2} are detected. In the htr-regime, CeO{sub 2-x} surfaces are by far less hydroxylated, which results from the desorption of H{sub 2}O and the formation oxygen vacancies. Simultaneously, Rh loses its hydrogen adsorption capability, whereas this property is practically constant in the ltr-regime. These findings are correlated to UPS measurements that give evidence for an electronic charge transfer from the CeO{sub 2-x} surface to Rh atoms. Finally this effect is interpreted in terms of the interaction between Rh atoms and oxygen vacancies at the CeO{sub 2-x} surface.},
doi = {},
url = {https://www.osti.gov/biblio/468024}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 31 00:00:00 EST 1996},
month = {Tue Dec 31 00:00:00 EST 1996}
}

Conference:
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