Author:
Arisetty Srikanth,Liu Yuxiu,Gu Wenbin,Mathias Mark
Abstract
Oxide growth on Pt catalysts in an N2/H2O atmosphere was investigated as a function of potential, and temperature. A coulometric method was employed to measure oxide coverages on Pt/Vulcan and PtCo/HSC catalysts. Data suggests that oxide coverage grows monotonically from zero at 0.6VRHE to a monolayer of oxide coverage at 0.95 VRHE. Potentiostatic-hold measurements indicate that oxide growth follows two steps, first Pt to PtO followed by PtO to PtO2 occurring more slowly. Characterization of the thermodynamics and kinetics of the above two reactions indicate faster growth in PtCo compared to Pt catalysts. The kinetics of place exchange oxide is thus shown to be enhanced by the alloying element cobalt. The effects of temperature and particle curvature were significant but secondary relative to the impact of potential. The results provide the understanding needed to correlate Pt oxide growth to ORR kinetics and catalyst degradation.
Publisher
The Electrochemical Society
Cited by
17 articles.
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