Enhanced chemical durability of perfluorosulfonic acid membranes through incorporation of terephthalic acid as radical scavenger

Chemical durability of perfluorosulfonic acid (PFSA) membranes is of crucial importance for their applications in proton exchange membrane fuel cells (PEMFCs). Herein, we report an easy method to enhance the chemical durability of PFSA membranes by incorporation of terephthalic acid (TPA) as a hydroxyl radical (center dot OH) scavenger. Recast TPA/PFSA composite membranes were prepared with TPA molecules uniformly dispersed. Fenton acceleration test, an effective method to evaluate the membrane durability, was conducted. PFSA ionomer degradation was characterized by FTIR, XPS, and ion chromatography. It is found that the functional group loss and decomposition ratio of C-F and sulfonic acid groups in TPA/PFSA composite membranes are less than those in PFSA membranes. Proton conductivity, methanol permeability, and mechanical durability investigations testify the remarkably mitigated degradation for TPA/PFSA membranes, owing to the presence of TPA. These results clearly suggest that incorporation of such radical trappers as TPA into PFSA membranes can effectively improve their chemical durability, thus making them promising in fuel cell applications. (C) 2013 Elsevier B.V. All rights reserved.