Impact of Fuel Cell Operating Potentials on Carbon Corrosion in Carbon Papers: Structural and Surface Characteristics

The gas diffusion layer (GDL) has garnered extensive attention as one of the key materials for membrane electrode assembly (MEA) in proton exchange membrane fuel cells (PEMFCs). The durability of the GDL has a significant impact on the lifetime of PEMFCs. However, there exists a gap in independent and systematic research on the durability of carbon papers (CPs), which serve as GDL substrates. In this study, carbon corrosion tests were conducted on commercial SGL 29AA CPs by applying a series of fixed potentials. Through physical, electrochemical, and spectroscopic analyses, the effect of applied potential on the carbon corrosion mechanism and its corresponding impact on fuel cell performance were explored. We observed that carbon corrosion tends to occur more on carbonized resins. The oxidation of carbonized resins mainly produced C–O bonds at low potential oxidation (<i>E</i> = 1.00 V), leading to a slight decrease in the contact angle by 11.2°. Higher potential oxidation (<i>E</i> ≥ 1.25 V) resulted in carbonized resin detachment and an increase in surface CO bonds, which led to a hydrophilic contact angle and a more than 3-fold increase in resistivity. Furthermore, we discovered that TGP-H-060 CPs with a high graphitization degree improve high potential carbon corrosion resistance. Thus, our findings suggest that the primary strategy for augmenting the corrosion resistance of CPs is elevating the graphitization level of carbonized resins.