Improving Electrocatalysts for O2 Reduction by Fine-Tuning the Pt-Support Interaction: Pt Monolayer on the Surfaces of a Pd3Fe(111) Single-Crystal Alloy

Journal Article · Wed Sep 09 04:00:00 EDT 2009 · Journal of the American Chemical Society, 131(35):12755-12762

DOI:https://doi.org/10.1021/ja9039746· OSTI ID:1001540

Zhou, Wei-Ping; Yang, Xiaofang; Vukmirovic, Miomir B; Koel, Bruce E; Jiao, Jiao; Peng, Guowen; Mavrikakis, Manos; Adzic, Radoslav R

We improved the effectiveness of Pt monolayer electrocatalysts for the oxygen-reduction reaction (ORR) using a novel approach to fine-tuning the Pt monolayer interaction with its support, exemplified by an annealed Pd3Fe(111) single-crystal alloy support having a segregated Pd layer. Low-energy ion scattering and low-energy electron diffraction studies revealed that a segregated Pd layer, with the same structure as Pd (111), is formed on the surface of high-temperature-annealed Pd3Fe(111). This Pd layer is considerably more active than Pd(111); its ORR kinetics is comparable to that of a Pt(111) surface. The enhanced catalytic activity of the segregated Pd layer compared to that of bulk Pd apparently reflects the modification of Pd surface’s electronic properties by underlying Fe. The Pd3Fe(111) suffers a large loss in ORR activity when the subsurface Fe is depleted by potential cycling (i.e., repeated excursions to high potentials in acid solutions). The Pd3Fe(111) surface is an excellent substrate for a Pt monolayer ORR catalyst, as verified by its enhanced ORR kinetics on PTML/Pd/Pd3Fe(111). Our density functional theory studies suggest that the observed enhancement of ORR activity originates mainly from the destabilization of OH binding and the decreased Pt-OH coverage on the Pt/Pd/Pd3Fe(111) surface. The activity of PtML/Pd(111) and Pt(111) is limited by OH removal, whereas the activity of PtML/Pd/Pd3Fe(111) is limited by the O-O bond scission, which places these two surfaces on the two sides of the volcano plot.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1001540
• Journal Information: Journal of the American Chemical Society, 131(35):12755-12762, Journal Name: Journal of the American Chemical Society, 131(35):12755-12762 Journal Issue: 35 Vol. 131; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CATALYST SUPPORTS
CATALYTIC EFFECTS
DENSITY FUNCTIONAL METHOD
ELECTROCATALYSTS
Environmental Molecular Sciences Laboratory
INTERACTIONS
IRON ALLOYS
KINETICS
PALLADIUM ALLOYS
PERFORMANCE
PLATINUM
REDOX REACTIONS