Title: How Does Nanoporous Gold Dissociate Molecular Oxygen?

Abstract

Nanoporous Au and other dilute AgAu alloys are highly active and selective oxidation catalysts. Their ability to dissociate O₂ is to a large extent unexplained, given that unsupported Au cannot generally dissociate O₂, while large ensembles of Ag atoms (>4) are generally necessary to lower the O₂ dissociation barrier significantly. In this work, we identify a site on the surface of dilute AgAu alloys that is stable under reaction conditions and has a low O₂ dissociation barrier, in agreement with experimental measurements. Although Ag generally prefers to disperse throughout Au, the presence of adsorbed O near surface steps creates sites of high local Ag concentration, where the Ag atoms sit in the rows next to the step Au atoms. O₂ adsorbs on the Au step atoms, but the transition state involves significant Ag–O interaction, resulting in a barrier lower than expected from the adsorption energies of either the initial or final state.

Authors:

Montemore, Matthew M. ^[1]; Madix, Robert J. ^[1]; Kaxiras, Efthimios ^[1]

---

+ Show Author Affiliations

1. Harvard Univ., Cambridge, MA (United States)

Publication Date:

Wed Jul 13 00:00:00 EDT 2016

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Energy Frontier Research Centers (EFRC) (United States). Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1387899

Grant/Contract Number:  

SC0012573; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 120; Journal Issue: 30; Related Information: IMASC partners with Harvard University (lead); Fritz Haber Institute; Lawrence Berkeley National Laboratory; Lawrence Livermore National Laboratory; University of Kansas; Tufts University; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; catalysis (heterogeneous); mesostructured materials; materials and chemistry by design; synthesis (novel materials)