Formation of a 2D meta-stable oxide by differential oxidation of AgCu alloys
File(s)
Author(s)
Type
Journal Article
Abstract
Metal alloy catalysts can develop complex surface structures when exposed to reactive atmospheres. The structures of the resulting surfaces have intricate relationships with a myriad of factors, such as the affinity of the individual alloying elements to the components of the gas atmosphere and the bond strengths of the multitude of low-energy surface compounds that can be formed. Identifying the atomic structure of such surfaces is a prerequisite for establishing structure–property relationships, as well as for modeling such catalysts in ab initio calculations. Here, we show that an alloy, consisting of an oxophilic metal (Cu) diluted into a noble metal (Ag), forms a meta-stable two-dimensional oxide monolayer, when the alloy is subjected to oxidative reaction conditions. The presence of this oxide is correlated with selectivity in the corresponding test reaction of ethylene epoxidation. In the present study, using a combination of in situ, ex situ, and theoretical methods (NAP-XPS, XPEEM, LEED, and DFT), we determine the structure to be a two-dimensional analogue of Cu2O, resembling a single lattice plane of Cu2O. The overlayer holds a pseudo-epitaxial relationship with the underlying noble metal. Spectroscopic evidence shows that the oxide’s electronic structure is qualitatively distinct from its three-dimensional counterpart, and because of weak electronic coupling with the underlying noble metal, it exhibits metallic properties. These findings provide precise details of this peculiar structure and valuable insights into how alloying can enhance catalytic properties.
Date Issued
2020-05-20
Date Acceptance
2020-04-21
Citation
ACS Applied Materials and Interfaces, 2020, 12 (20), pp.23595-23605
ISSN
1944-8244
Publisher
American Chemical Society
Start Page
23595
End Page
23605
Journal / Book Title
ACS Applied Materials and Interfaces
Volume
12
Issue
20
Identifier
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000537394100122&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=a2bf6146997ec60c407a63945d4e92bb
Subjects
2-dimensional material
ABERRATION CORRECTION
AG(111)
CATALYSTS
COPPER
CU(111)
dilute alloy
ETHYLENE EPOXIDATION
Materials Science
Materials Science, Multidisciplinary
meta-stable
Nanoscience & Nanotechnology
oxide monolayer
OXYGEN-ADSORPTION
Science & Technology
Science & Technology - Other Topics
SILVER
SURFACE-CHEMISTRY
Technology
XPS
Publication Status
Published
Date Publish Online
2020-04-21