Issue 11, 2014

Elucidating the oxide growth mechanism on platinum at the cathode in PEM fuel cells

Abstract

Simulations of platinum oxidation in literature have yet to fully replicate an experimental cyclic voltammogram. In this manuscript a mechanism for platinum oxidation is proposed based upon the results of in operando X-ray absorption spectroscopy, where it was found that PtO2 is present at longer hold times. A new method to quantify extended X-ray absorption fine structure data is presented, and the extent of oxidation is directly compared to electrochemical data. This comparison indicated that PtO2 was formed at the expense of an initial oxide species. From previous literature studies it can be concluded that the rate of platinum oxidation is not a function of only potential and coverage. To that end, the concept of a heterogeneous oxide layer was introduced into the model, whereby place-exchanged PtO2 structures of varying energy states are formed through a single transition state. This treatment allowed, for the first time, the simulation of the correct current–potential behavior at varying scan rates and upper potential limits.

Graphical abstract: Elucidating the oxide growth mechanism on platinum at the cathode in PEM fuel cells

Supplementary files

Article information

Article type
Paper
Submitted
08 Nov 2013
Accepted
22 Jan 2014
First published
22 Jan 2014

Phys. Chem. Chem. Phys., 2014,16, 5301-5311

Elucidating the oxide growth mechanism on platinum at the cathode in PEM fuel cells

E. L. Redmond, B. P. Setzler, F. M. Alamgir and T. F. Fuller, Phys. Chem. Chem. Phys., 2014, 16, 5301 DOI: 10.1039/C3CP54740J

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