Abstract
We investigated a new method for the analysis of the degradation mechanism of the electrocatalysts of a polymer electrolyte fuel cell (PEFC) by ex situ transmission electron microscopy (TEM). With a newly developed sample holder, electrochemical measurements and observation of the same field of view before and after the measurements were realized for a small piece of a membrane electrode assembly in gas atmospheres simulating durability tests for the PEFC. The ex situ TEM analyses revealed that the trend of structural changes such as corrosion of the carbon support and coalescence of Pt particles and that of a decrease in the electrochemically active area of Pt were in the same manner as the results for durability tests with a single cell. Therefore, the new method established in this study serves as a fundamental technique for tracing the changes in the morphology and electrochemical property of the electrocatalysts.
