The interaction of sulfur with Ag/Pt(111) surfaces: Silver-promoted sulfidation of platinum

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1995.1177· OSTI ID:111030

Kuhn, M; Rodriguez, J A ^[1]

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1. Brookhaven National Lab., Upton, NY (United States)

The coadsorption of sulfur and silver on Pt(111) has been examined using thermal desorption mass spectroscopy (TDS), X-ray photoelectron spectroscopy (XPS), and X-ray excited Auger electron spectroscopy (XAES). The results of XPS and XAES indicate that at temperatures between 300 and 700 K, S{sub 2} gas reacts with Pt(111) producing a chemisorbed layer of sulfur without forming bulk-like platinum sulfides. The sulfidation of platinum occurs after vapor depositing Ag on S/Pt(111) surfaces or after exposing Ag/Pt(111) surfaces to S{sub 2} gas. At temperatures from 400 to 700 K, the reaction of S{sub 2} gas with Ag produces silver sulfides that catalyze the sulfidation of platinum by providing surface sites for the dissociation of S{sub 2}, and by favoring the diffusion of S into the bulk of the Pt substrate. The silver and platinum sulfides in the S/Ag/Pt(111) systems decompose at temperatures between 750 and 850 K, with S{sub 2} and S evolving into gas phase and metallic Ag remaining on top of a Pt(111) substrate partially covered by chemisorbed S. At submonolayer coverages of Ag and S on Pt(111),{theta}{sub Ag} + {theta}{sub s} < 1 ML, the presence of sulfur significantly weakens the strength of the Pt{leftrightarrow}Ag interactions, and the desorption temperature of Ag is {approximately}90 K smaller than on clean Pt(111). The TDS results indicate that a S adatom reduces the ability for bimetallic bonding of several (3-4) platinum surface atoms. 41 refs., 12 figs.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 111030
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 154; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
40 CHEMISTRY
AUGER ELECTRON SPECTROSCOPY
MASS SPECTROSCOPY
MILLER INDICES
PHOTOELECTRON SPECTROSCOPY
PLATINUM
SILVER
SULFIDATION
X-RAY SPECTROSCOPY