Experimental probing of the effect of PFSA ionomer poisoning at different Pt loadings in a PEMFC

The charge-transfer resistance (Rct) in electrochemical impedance spectroscopy (EIS) was applied as an activity indicator to study the suppression of rotating disk electrodes (RDEs) and membrane electrode assemblies (MEAs) with different Pt loadings by Nafion. The use of Rct avoids the uncertainty in activity characterization caused by mass transfer in highly loaded catalyst agglomerates. Nafion exhibited a stronger poisoning effect at lower Pt loadings in both the RDEs and MEAs. The simultaneous reduction in working voltage further aggravates this poisoning, especially under low-Pt conditions. After poisoning, the normalized Rct at 20 lg/cm2 increased by 8 times at 0.9 V and 21 times at 0.82 V. When the Nafion adsorption coverage on the surface of Pt remained constant, the suppression of activity was enhanced as the Pt loading decreased. Therefore, it is critical to consider Nafion poisoning when constructing MEAs with low platinum loading and to take appropriate strategies to alleviate poisoning and achieve high-performance.(c) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, the charge-transfer resistance (Rct) was used as an activity indicator to investigate the suppression of rotating disk electrodes (RDEs) and membrane electrode assemblies (MEAs) with different Pt loadings by Nafion. Nafion showed a stronger poisoning effect at lower Pt loadings, which was exacerbated by a simultaneous reduction in working voltage under low-Pt conditions.