Characterization of Catalyst Layer Structural Changes in PEMFC as a Function of Durability Testing

Abstract

Structural (morphology) changes of the catalyst layer in a proton exchange membrane fuel cell (PEMFC) during durability tests were characterized using transmission electron microscope (TEM) and scanning electron microscope (SEM). Observations were that platinum was redistributed in the catalyst layer and membrane depending on the fuel cell operating conditions. Pt particle agglomeration, dissolution and migration into the membrane resulted in a reduction in Pt surface area. A Pt depletion layer was also observed in the catalyst layer using an accelerated aging test. Following carbon corrosion, a well known failure mechanism, the original porous structure in the catalyst layer collapsed, resulting in high mass transport loss. It has been found that cathode corrosion is more severe underneath the plate landing, and especially on the anode landing area where local fuel starvation may occur.