Examining the redox and formate mechanisms for water-gas shift reaction on Au/CeO2 using density functional theory

Ying Chen, Jun Cheng, P. Hu*, Haifeng Wang

*Corresponding author for this work

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

We perform DFT calculations to investigate the redox and formate mechanisms of water-gas-shift (WGS) reaction on Au/CeO2 catalysts. In the redox mechanism, we analyze all the key elementary steps and find that the OH cleavage is the key step. Three possible pathways of OH cleavage are calculated: (1) OHad '' + *'--> H-ad' + O-ad"; (2) H-ad' + OHad '' --> H-2(g) + O-ad '' + *'; and (3) OHad" + OHad '' --> 2O(ad '') + H-2(g) (*': the free adsorption sites on the oxides; ad': adsorption on the metal; ad": adsorption on the oxide, respectively). In the formate mechanism, we identify all the possible pathways for the formation and decomposition of surface formates in the WGS reaction. It is found that there is a shortcoming in the redox and formate mechanisms which is related to surface oxygen reproduction. Four possible pathways for producing surface oxygen are studied, and all the barriers of the four pathways are more than 1 eV. Our results suggest that the processes to reproduce surface oxygen in the reaction circle are not kinetically easy. (C) 2008 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)2828-2834
Number of pages7
JournalSurface Science
Volume602
Issue number17
Early online date11 Jul 2008
DOIs
Publication statusPublished - 1 Sep 2008

Keywords

  • density functional calculations
  • catalysis
  • surface chemical reactions
  • gold
  • ceria
  • CO
  • CO2
  • in-situ drifts
  • CO oxidation
  • PT/ceria catalysts
  • surface formates
  • supported gold
  • AU
  • nanoparticles
  • CEO2
  • decomposition
  • reactant

Cite this

Examining the redox and formate mechanisms for water-gas shift reaction on Au/CeO2 using density functional theory. / Chen, Ying; Cheng, Jun; Hu, P.; Wang, Haifeng.

In: Surface Science , Vol. 602, No. 17, 01.09.2008, p. 2828-2834.

Research output: Contribution to journalArticle

Chen, Ying ; Cheng, Jun ; Hu, P. ; Wang, Haifeng. / Examining the redox and formate mechanisms for water-gas shift reaction on Au/CeO2 using density functional theory. In: Surface Science . 2008 ; Vol. 602, No. 17. pp. 2828-2834.
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AB - We perform DFT calculations to investigate the redox and formate mechanisms of water-gas-shift (WGS) reaction on Au/CeO2 catalysts. In the redox mechanism, we analyze all the key elementary steps and find that the OH cleavage is the key step. Three possible pathways of OH cleavage are calculated: (1) OHad '' + *'--> H-ad' + O-ad"; (2) H-ad' + OHad '' --> H-2(g) + O-ad '' + *'; and (3) OHad" + OHad '' --> 2O(ad '') + H-2(g) (*': the free adsorption sites on the oxides; ad': adsorption on the metal; ad": adsorption on the oxide, respectively). In the formate mechanism, we identify all the possible pathways for the formation and decomposition of surface formates in the WGS reaction. It is found that there is a shortcoming in the redox and formate mechanisms which is related to surface oxygen reproduction. Four possible pathways for producing surface oxygen are studied, and all the barriers of the four pathways are more than 1 eV. Our results suggest that the processes to reproduce surface oxygen in the reaction circle are not kinetically easy. (C) 2008 Elsevier B.V. All rights reserved.

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KW - nanoparticles

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