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The (111) Surface of NaAu2: Structure, Composition, and Stability

TitleThe (111) Surface of NaAu2: Structure, Composition, and Stability
Publication TypeJournal Article
Year of Publication2015
AuthorsKwolek, EJ, Widmer, R, Groning, O, Deniz, O, Walen, H, Yuen, CD, Huang, WK, Schlagel, DL, Wallingford, M, Thiel, PA
JournalInorganic Chemistry
Volume54
Pagination1159-1164
Date Published02
Type of ArticleArticle
ISBN Number0020-1669
Accession NumberWOS:000348887400059
Keywordsalloy formation, catalysts, na/au(111) system, temperature co oxidation
Abstract

The (111) surface of single-crystal NaAu2 is a model for catalytically active, powdered NaAu2. We prepare and characterize this surface with a broad suite of techniques. Preparation in ultrahigh vacuum consists of the traditional approach of ion bombardment (to remove impurities) and thermal annealing (to restore surface order). Both of these steps, however, cause loss of sodium (Na), and repeated treatments eventually trigger conversion of the surface and near-surface regions to crystalline gold. The bulk has a limited ability to repopulate the surface Na. Under conditions where Na depletion is minimized, electron diffraction patterns are consistent with the bulk-terminated structure, and scanning tunneling microscopy reveals mesa-like features with lateral dimensions of a few tens of nanometers. The tops of the mesas do not possess fine structure characteristic of a periodic lattice, suggesting that the surface layer is disordered under the conditions of these experiments.

DOI10.1021/ic5025444
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Surface Structures