Geometrical Structure of the Gold–Iron(III) Oxide Interfacial Perimeter for CO Oxidation

Xuejiao Wei, Bin Shao, Yan Zhou, Yong Li, Chuanchuan Jin, Jingyue Liu, Wenjie Shen

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Abstract

The geometrical structure of the Au-Fe2O3 interfacial perimeter, which is generally considered as the active sites for low-temperature oxidation of CO, was examined. It was found that the activity of the Au/Fe2O3 catalysts not only depends on the number of the gold atoms at the interfacial perimeter but also strongly depends on the geometrical structure of these gold atoms, which is determined by the size of the gold particle. Aberration-corrected scanning transmission electron microscopy images unambiguously suggested that the gold particles, transformed from a two-dimensional flat shape to a well-faceted truncated octahedron when the size slightly enlarged from 2.2 to 3.5 nm. Such a size-induced shape evolution altered the chemical bonding environments of the gold atoms at the interfacial perimeters and consequently their catalytic activity. For Au particles with a mean size of 2.2 nm, the interfacial perimeter gold atoms possessed a higher degree of unsaturated coordination environment while for Au particles with a mean size of 3.5 nm the perimeter gold atoms mainly followed the atomic arrangements of Au {111} and {100} facets. Kinetic study, with respect to the reaction rate and the turnover frequency on the interfacial perimeter gold atom, found that the low-coordinated perimeter gold atoms were intrinsically more active for CO oxidation. 18O isotopic titration and Infrared spectroscopy experiments verified that CO oxidation at room temperature occurred at the Au-Fe2O3 interfacial perimeter, involving the participation of the lattice oxygen of Fe2O3 for activating O2 and the gold atoms for CO adsorption and activation.

Original languageEnglish (US)
Pages (from-to)11289-11293
Number of pages5
JournalAngewandte Chemie - International Edition
Volume57
Issue number35
DOIs
StatePublished - Aug 27 2018

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Keywords

  • active sites
  • CO oxidation
  • geometrical structures
  • gold nanoparticle
  • supported catalysts

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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