Membrane degradation: Proton exchange membrane (PEM) fuel cells convert electrochemical energy into electrical energy. During fuel cell operation reactive oxidizing species are formed that degrade the PEM. We investigated the degradation of a generic aromatic sulfonate-type membrane and its repair by the antioxidant (AO) Cu(II)−porphyrin. We found that the porphyrin AO significantly increases the stability towards radical-induced degradation.
The use of hydrocarbon-based proton conducting membranes in fuel cells is currently hampered by the insufficient durability of the material in the device. Membrane aging is triggered by the presence of reactive intermediates, such as HO⋅, which attack the polymer and eventually lead to chain breakdown and membrane failure. An adequate antioxidant strategy tailored towards hydrocarbon-based ionomers is therefore imperative to improve membrane lifetime. In this work, we perform studies on reaction kinetics using pulse radiolysis and γ-radiolysis as well as fuel cell experiments to demonstrate the feasibility of increasing the stability of hydrocarbon-based membranes against oxidative attack by implementing a Nature-inspired antioxidant strategy. We found that metalated-porphyrins are suitable for damage transfer and can be used in the fuel cell membrane to reduce membrane aging with a low impact on fuel cell performance.Zum Volltext