Modelling oxide formation and growth on platinum

We present a mathematical model of oxide formation and growth on platinum. The motivation stems from the necessity to understand platinum dissolution in the cathode catalyst layer of polymer electrolyte fuel cells. As is known, platinum oxide formation and reduction are strongly linked to platinum d...

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Bibliographic Details
Published in:The Journal of chemical physics 2017-04, Vol.146 (14), p.144102-144102
Main Authors: Baroody, Heather A., Jerkiewicz, Gregory, Eikerling, Michael H.
Format: Article
Language:English
Subjects:
Cathodic dissolution
Dissolution
Electrolytic cells
Metal oxides
Migration
Oxidation
Oxygen ions
Parametric analysis
Platinum
Proton exchange membrane fuel cells
Reaction kinetics
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Summary:We present a mathematical model of oxide formation and growth on platinum. The motivation stems from the necessity to understand platinum dissolution in the cathode catalyst layer of polymer electrolyte fuel cells. As is known, platinum oxide formation and reduction are strongly linked to platinum dissolution processes. However, a consistent model of the oxidation processes on platinum does not exist. Our oxide growth model links interfacial exchange processes between platinum and oxygen ions with the transport of oxygen ion vacancies via diffusion and migration. A parametric analysis is performed to rationalize vital trends in oxide growth kinetics. The rate determining step of oxide formation and growth is identified as the extraction of platinum atoms at the metal-oxide interface. A kinetic effect is observed while adjusting the potential when growing the oxide layer, and the solution indicates that a structural change occurs at high potentials, around 1.5 VRHE. The model compares well to experimental data for various materials from various sources.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4979121