Electrochemical oxidation of methanol on tin-modified platinum single-crystal surfaces

Journal Article · Thu May 02 04:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100162a056· OSTI ID:5988480

Haner, A N; Ross, P N ^[1]

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1. Lawrence Berkeley Lab., CA (United States)

To understand the role of tin as a promoter in the electrochemical oxidation of methanol, the authors have studied the geometric and electronic effect of tin atoms in different chemical states on/in the platinum surface by using single-crystal faces of the ordered alloy Pt{sub 3}Sn and single-crystal faces of pure Pt modified by electrodeposited/adsorbed tin, i.e., the so-called adatom state. They found that none of the alloy surfaces were more effective catalysts than any of the pure platinum surfaces under the conditions of measurement employed here and that alloying platinum with tin to any extent significantly reduced the activity. As reported previously by others, they observed tin to spontaneously adsorb on platinum surfaces from dilute sulfuric acid supporting electrolyte containing Sn(II) in concentrations above ca. 5 {mu}M. At a given concentration, the coverage by tin decreased as the atomic density of the platinum surface increased. However, they did not observe any enhancement of methanol oxidation on any platinum modified by this irreversibly adsorbed tin. They did observe a diffusion-limited enhancement on Pt(111) and on Pt(100) due to Sn(II) in the electrolyte at 1 {mu}M concentration. At this concentration, tin did not appear to be adsorbed to any observable extent, and the catalysis appeared to occur via the direct interaction of a dissolved tin species with the surface. They propose a mechanism of catalysis that is a hybrid homogeneous-heterogeneous sequence based on known homogeneous Pt-Sn catalysts.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5988480
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:9; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

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ADSORPTION
ALCOHOLS
ALLOYS
AUGER ELECTRON SPECTROSCOPY
CATALYSIS
CHARGED PARTICLES
CHEMICAL REACTIONS
CHEMISTRY
COATINGS
COHERENT SCATTERING
CRYSTALS
DATA
DIFFRACTION
ELECTROCHEMISTRY
ELECTRODEPOSITED COATINGS
ELECTRON DIFFRACTION
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
ELEMENTS
EXPERIMENTAL DATA
HETEROGENEOUS CATALYSIS
HOMOGENEOUS CATALYSIS
HYDROXY COMPOUNDS
INFORMATION
IONS
METALS
METHANOL
MILLER INDICES
MONOCRYSTALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDATION
PLATINUM
PLATINUM ALLOYS
PLATINUM METAL ALLOYS
PLATINUM METALS
SCATTERING
SORPTION
SPECTROSCOPY
SURFACES
TIN
TIN ALLOYS
TIN IONS
TRANSITION ELEMENTS
VOLTAMETRY