The effect of Ru and Sn additions to Pt on the electrocatalysis of methanol oxidation: An in situ XAS investigation

Conference · Tue Jul 01 04:00:00 EDT 1997

OSTI ID:493386

Mukerjee, S; McBreen, J

Elements such as Ru and Sn used as ad-atoms or as alloying elements are known to enhance methanol oxidation reaction (MOR). Ru, both as alloying element as well as upd deposited on Pt/C is widely acknowledged for enhancing MOR. Sn on the other hand is more controversial, with evidence indicating enhancements for MOR when present as upd layer and marginally effective when present as an alloying element. In situ XAS is used to investigate some of these inconsistencies in the electrocatalysis of MOR. Results indicate that alloying Sn with Pt (Pt{sub 3}Sn primary phase) causes partial filling of the Pt 5 d-band vacancies and increase in the Pt-Pt bond distances which is directly opposite to a similar situation with Ru. Upd Sn however does not perturb Pt structurally or electronically. Ru and Sn (both as alloying element and as upd ad-layer) are associated with oxygenated species, the nature and strength of the Ru. and Sn - oxygen interactions are potential dependent. Hence alloying with Sn renders Pt surface unfavorable for methanol adsorption in contrast to alloying with Ru. Both Ru and Sn however promote MOR via their ability to nucleate oxygenated species on their surface at lower potentials as compared to pure Pt.

• Research Organization: Brookhaven National Lab., Upton, NY (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
• DOE Contract Number: AA03-78CH00017
• OSTI ID: 493386
• Report Number(s): BNL--64293; CONF-970738--4; ON: DE97006755
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
36 MATERIALS SCIENCE
66 PHYSICS
BOND LENGTHS
CATALYTIC EFFECTS
ELECTROCATALYSTS
FUEL CELLS
METHANOL
OXIDATION
PLATINUM ALLOYS
RUTHENIUM ALLOYS
SPECTRA
TIN ALLOYS
VACANCIES
X-RAY DIFFRACTION