EC-STM study of the initial stages of the electrochemical Au(1 1 1)-Cd alloy formation

Christian Georg Schlaup, Sebastian Horch

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We have studied the formation of an Au(1 1 1)-Cd alloy in a H2SO4 electrolyte by means of electrochemical STM (EC-STM). To this end, we first characterized the underpotential deposited (upd) Cd overlayers on Au(1 1 1) electrodes. We confirmed the existence of two upd phases on the reconstructed Au(1 1 1) surface, of which the first can be described with a (4×√3) unit cell and the second one with a (3×√3) unit cell in coexistence with a (2×√3) unit cell. At more negative potentials, an alloy with the Au(1 1 1) substrate is formed. In order to obtain a deeper insight into the alloying process, we had to avoid further Cd deposition at these potentials. This was achieved by exchanging the electrolyte after Cd deposition for a Cd-free solution under potential control. We found that the Au-Cd alloy exhibits an atomic structure with a close to square unit cell and locally interferes with the pattern of the Au(1 1 1) "herringbone" reconstruction. This Au-Cd alloy increases the overpotential for the hydrogen evolution reaction (HER) by about 130 mV.
Original languageEnglish
JournalSurface Science
Volume632
Pages (from-to)126-134
Number of pages9
ISSN0039-6028
DOIs
Publication statusPublished - 2014

Keywords

  • Cadmium
  • Electrochemical phenomena
  • Scanning tunneling microscopy
  • Underpotential deposition
  • Alloy formation
  • Au(1 1 1 )
  • STM study

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