Structure of chemisorbed sulfur on a Pt(111) electrode
Journal Article
·
· Journal of the American Chemical Society
- Univ. of Illinois, Urbana, IL (United States)
- Universite de Sherbrooke, Quebec (Canada)
Electron spectroscopic and diffraction results obtained in ultra-high-vacuum, combined with cyclic voltammetric data, are reported for sulfur adlayers deposited from aqueous sulfide and bisulfide media on Pt(111). The highest coverage obtained by Auger electron spectroscopy, 0.94 {+-} 0.05 monolayer, is very close to the coverage obtained from coulometry, and is associated with a (1 x 1) surface phase. This coverage is much higher than that obtained in previous electrochemical studies but is the same as found by other investigators using S{sub 2} beam dosing in vacuum. The near complete sulfur monolayer is characterized by a rapid and incomplete oxidation in a narrow potential range near 0.70 V vs a Ag/AgCl reference. Neither full sulfur monolayer coverage nor a sharp voltammetric transition could be obtained when traces of oxygen were present in the electrochemical cell. Oxidation of the (1 x 1) adlayer (at 1 monolayer) gave rise to a previously unreported (2 x 2) structure, at 1/2 monolayer. The results of the core-level electron energy loss spectroscopy studies suggest that sulfur adatoms retain some of the negative charge and that this charge plays a major role in controlling hydrogen adsorption coverage in the presence of coadsorbed sulfur on Pt(111). 61 refs., 7 figs., 2 tabs.
- DOE Contract Number:
- AC02-76ER01198
- OSTI ID:
- 458626
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 1 Vol. 119; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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