In situ atomic force microscope study of Pb underpotential deposition on Au(111): Structural properties of the catalytically active phase

Chun Hsien Chen, Newell Washburn, Andrew A. Gewirth

Research output: Contribution to journalArticle

Abstract

Atomic resolution atomic force microscope (AFM) images of Pb underpotential deposition on Au(111) electrodes are presented. Pb grows on the Au(111) surface by forming islands which are initially one Pb adatom high (0.30 nm) but which rapidly grow in height to 0.53 nm through association of the Pb with solvent or hydroxide. The Pb aggregates have a hexagonal close-packed atomic structure exhibiting an atom-atom spacing of 0.35 ± 0.03 nm. The islands can be easily swept away by the AFM tip when the tip sample force is set at 80 nN, but Pb deposited at step edges is not swept away under these conditions. This suggests that the Pb (island)-Au interaction is relatively weak. The full monolayer of Pb adatoms form a hexagonal close packed layer on Au(111) surfaces with an 0.35 ± 0.02 nm atom-atom spacing, the same as found atop the islands. The Pb overlayer is rotated 4.5° relative to the Au(111) substrate and a Moiré pattern arising from interference between the Pb overlayer and the substrate is observed. The highest level of catalytic activity for peroxide electroreduction is observed when the surface is maximally covered by the Pb islands.

Original languageEnglish (US)
Pages (from-to)9754-9760
Number of pages7
JournalJournal of physical chemistry
Volume97
Issue number38
DOIs
StatePublished - Jan 1 1993

ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry

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