Structural kinetics of a Pt/C cathode catalyst with practical catalyst loading in an MEA for PEFC operating conditions studied by in situ time-resolved XAFS.
Phys Chem Chem Phys
; 15(43): 18827-34, 2013 Nov 21.
Article
em En
| MEDLINE
| ID: mdl-24085156
ABSTRACT
The structural kinetics of surface events on a Pt/C cathode catalyst in a membrane electrode assembly (MEA) with a practical catalyst loading (0.5 mgPt cm(-2)) for a polymer electrolyte fuel cell were investigated by in situ time-resolved X-ray absorption fine structure analysis (XAFS; time resolution 100 ms) for the first time. The rate constants of structural changes in the Pt/C cathode catalyst in the MEA during voltage cycling were successfully estimated. For voltage-cycling processes, all reactions (electrochemical reactions and structural changes in the Pt catalyst) in the MEA were found to be much faster than those in an MEA with a thick cathode catalyst layer, but the in situ time-resolved XAFS analysis revealed that significant time lags similarly existed between the electrochemical reactions and the structural changes in the Pt cathode catalyst. The time-resolved XAFS also revealed differences in the structural kinetics of the Pt/C cathode catalyst for the voltage-cycling processes under N2 and air flows at the cathode.
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MEDLINE
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En
Ano de publicação:
2013
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Article