Structural and kinetic aspects of bromide adsorption on Au(100)
Journal Article
·
· Journal of Physical Chemistry
- Univ. of Ulm (Germany)
- Brookhaven National Lab., Upton, NY (United States)
The adsorption and phase formation of bromide ions on Au(100) has been studied with in-situ surface X-ray diffraction in combination with electrochemical measurements. The investigations allowed a rather detailed assignment of all voltammetric features of the bromide adsorption on Au(100) to the respective structural properties, their stability, and their transition kinetics. The presence of a small bromide surface excess at Au(100)-(hex) causes the lifting of the substrate surface reconstruction. The corresponding charge density just before the onset of the transition ranges from -2 to -8 {mu}C cm{sup -2}. No ordering of the adlayer is required or involved. The lifting of the substrate reconstruction proceeds at high overpotentials via instantaneous nucleation and two-dimensional growth. The growth mechanism seems to change at low overpotentials toward a one-dimensional or surface diffusion controlled process. Two ordered bromide adlayer phases were found on the unreconstructed Au(100)-(1x1) surface. The low coverage phase ({theta} = 0.5) corresponds to a commensurate c({radical}2x2{radical}2)R45{degree} superstructure. A uniaxial commensurate c({radical}2xp)R45{degree} phase is formed at more positive potentials, in which the coverage increases from 0.5 to approximately 0.565 (relative to the gold layer density) with increasing electrode potential. 48 refs., 15 figs.
- OSTI ID:
- 375678
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 24 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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