A theoretical study of CO oxidation and O2 activation for transition metal overlayers on SrTiO3 perovskite

Long Zhang, Ming Wen Chang, Ya Qiong Su, Ivo A.W. Filot, Emiel J.M. Hensen (Corresponding author)

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)

Abstract

Understanding the catalytic properties of metal/metal oxide interfaces is gaining importance in heterogeneous catalysis. Density functional theory calculations were employed to understand the mechanism of CO oxidation on TM/SrTiO3 catalysts (TM/STO, TM = Au, Ag, Pd, Pt, Rh, and Ir). Au benefits from O2 dissociation at the Au/STO interface with lower barrier than on corresponding closed-packed Au surface. Doping of STO with fluorine lowers the activation barriers for O2 dissociation. Brønsted-Evans-Polanyi relations are identified for O2 dissociation and a density of states analysis provides insight into the activation of O2 at TM/STO interfaces. Full catalytic cycles for CO oxidation are formulated including O2 dissociative and associative mechanisms. Microkinetics simulations show that an O2 associative mechanism at Au/STO and Ag/STO interfaces is dominant for CO oxidation. For a more reactive metal like Pd, CO2 formation involving interface sites present higher barriers than on the metal itself because of too strong binding of O at the Pd/STO interface. Pt/STO and Rh/STO also follow such a conventional Langmuir-Hinshelwood mechanism, while Ir is too reactive leading to a shift of the reaction at the Ir/STO interface involving dissociated O2. The mechanistic insights are discussed with respect to recent experimental literature on Pd/STO and Au/STO for which different structure-performance relationships were formulated. We predict that F-doping of STO can further improve the catalytic performance of TM/STO catalysts for CO oxidation.

Original languageEnglish
Pages (from-to)229-240
Number of pages12
JournalJournal of Catalysis
Volume391
DOIs
Publication statusPublished - Nov 2020

Keywords

  • CO oxidation
  • O activation
  • SrTiO
  • Structure-performance
  • Transition metals

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