Characterization of Carbon Corrosion in a Segmented PEM Fuel Cell

Corrosion of the catalyst support is an important degradation mechanism in PEM fuel cells because it reduces the overall cell performance by decreasing the active catalyst surface area, catalyst connectivity, and the porosity and hydrophobicity of the catalyst layer. Carbon corrosion rates were investigated in a segmented cell with and without a microporous layer (MPL) on the cathode. The cells were aged in-situ using a protocol for accelerated stress testing (AST) for carbon-support corrosion consisting of consecutive holds at 1.3 V. Carbon corrosion was quantified by measuring CO2 evolution during the potential holds. Although more carbon was corroded in the cell with the MPL on the cathode, corrosion in the catalyst layer was lower than in the cell without the MPL because a portion of the evolved CO2 originated from the MPL rather than from the catalyst layer. This was corroborated by the higher remaining ECSA and lower kinetic losses after prolonged corrosion for the MPL case. Both GDL cases exhibited substantial performance degradation and ECSA loss. Cell with the MPL was more resistant to prolonged carbon corrosion.