Severe accelerated degradation of PEMFC platinum catalyst: A thin film IL-SEM study

The degradation of a commercial platinum polymer electrolyte membrane (PEM) fuel cell catalyst has been studied under severe simulated start–stop conditions (50,000 cycles from 0.2 V to 1.4 V vs. the reversible hydrogen electrode, RHE), employing a newly developed identical location scanning electron microscopy technique (IL-SEM). We show that significant platinum particle growth occurs on top of the catalyst film while platinum depletion takes place in the layers beneath. There is a possibility of misleading interpretation of thin film severe degradation experiments, when the catalyst loading and volume of electrolyte are neglected and when the non-identical location electron microscopy pictures are statistically analyzed.

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► A new method of IL-SEM has been employed.
► Severe degradation of PEMFC platinum catalyst is shown by cycling to 1.4 V RHE.
► Large Pt particle growth on top of catalyst film is observed (Ostwald ripening).
► After about 2000 cycles there is a change in degradation rate constant.
► There is a possibility of misleading interpretation of thin film severe catalyst degradation data.