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.

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Real driving emission regulations using portable emission measurement systems (PEMS) will be applied from October 2022 for light and medium-duty diesel vehicles in Japan. This means that during vehicle development it is more important to consider various situations. However, since an actual driving test depends on the surrounding traffic conditions and the weather, there is a high possibility that a test cannot be completed. For efficient vehicle development, it is necessary to develop an evaluation method that can simulate real driving emission in the laboratory. In this research, a random cycle generator (RCG) that can generate a real driving cycle that simulates various traffic situations was developed. Furthermore, the random cycle was run on an environmental chassis dynamometer. As a result, an alternative evaluation method for real driving emission (RDE) tests was proposed, which is not affected by actual traffic conditions or weather.

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