Membrane electrode assembly contamination

The membrane electrode assembly (MEA) in a proton exchange membrane (PEM) fuel cell has been identified as the key component that is probably most affected by the contamination process [1]. An MEA consists of anode and cathode catalyst layers (CLs), gas diffusion layers (GDLs), as well as a proton exchange membrane, among which the CLs present the most important challenges due to their complexity and heterogeneity. The CL is several micrometers thick and either covers the surface of the carbon base layer of the GDL or is coated on the surface of the membrane. The CL consists of (1) an ionic conductor (ionomer) to provide a passage for proton transport ... 

Depending on cell design and construction, the sealing material can come into contact with the catalyst layer of the membrane electrode assembly in these cases care must be taken that the material does not contain any substances which in the presence of the catalyst lead to unwanted side reactions. The sealing materials must neither contain any components which can act as catalyst poisons which will contaminate and thus deactivate the electrocatalyst, leading to reduced cell efficiency. 

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