Abbreviated Journal Title
J. Chem. Phys.
Keywords
PLATINUM-MONOLAYER ELECTROCATALYSTS; PALLADIUM ALLOY ELECTROCATALYSTS; TRANSITION-METAL SURFACES; KINETIC-PARAMETERS; ACIDIC MEDIA; ADSORPTION; PT(111); ORIGIN; WATER; O-2; Physics, Atomic, Molecular & Chemical
Abstract
We report here results of our density functional theory based computational studies of the electronic structure of the Pd-Co alloy electrocatalysts and energetics of the oxygen reduction reaction (ORR) on their surfaces. The calculations have been performed for the (111) surfaces of pure Pd, Pd(0.75)Co(0.25) and Pd(0.5)Co(0.5) alloys, as well as of the surface segregated Pd/Pd(0.75)Co(0.25) alloy. We find the hybridization of dPd and dCo electronic states to be the main factor controlling the electrocatalytic properties of Pd/Pd(0.75)Co(0.25). Namely the dPd-dCo hybridization causes low energy shift of the surface Pd d-band with respect to that for Pd(111). This shift weakens chemical bonds between the ORR intermediates and the Pd/Pd(0.75)Co(0.25) surface, which is favorable for the reaction. Non-segregated Pd(0.75)Co(0.25) and Pd(0.5)Co(0.5) surfaces are found to be too reactive for ORR due to bonding of the intermediates to the surface Co atoms. Analysis of the ORR free energy diagrams, built for the Pd and Pd/Pd(0.75)Co(0.25), shows that the co-adsorption of the ORR intermediates and water changes the ORR energetics significantly and makes ORR more favorable. We find the onset ORR potential estimated for the configurations with the O-OH and OH-OH co-adsorption to be in very good agreement with experiment. The relevance of this finding to the real reaction environment is discussed.
Journal Title
Journal of Chemical Physics
Volume
135
Issue/Number
13
Publication Date
1-1-2011
Document Type
Article
DOI Link
Language
English
First Page
10
WOS Identifier
ISSN
0021-9606
Recommended Citation
Zuluaga, Sebastian and Stolbov, Sergey, "Factors controlling the energetics of the oxygen reduction reaction on the Pd-Co electro-catalysts: Insight from first principles" (2011). Faculty Bibliography 2010s. 2180.
https://stars.library.ucf.edu/facultybib2010/2180
Comments
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