Study of the degradation of Nafion modified membranes

Abstract

The development of new proton exchange membranes for PEM technology in fuel cells and electrolysers with increased durability is paramount to system's lifetime and scalability. In this work, new modified Nafion membranes are proposed with increased resilience to chemical degradation by H2O2/Fe2+, mimicking ex-situ radical attack to membrane structure.Morphological analysis by SEM revealed the formation of a heterogeneous surface for all membranes. The new modified membranes with BP1 and BP2 dopants (Fig. la) showed a weight loss of up to 3% at 112 h compared to the loss of near 18% of the Nafion membrane, at 80 °C. These results were corroborated with the measurements of fluoride ion loss. An increased release of fluoride ions vs exposure time is observed. The new membranes doped with BP1 and BP2 showed similar loss of the fluoride ion with values up to 14 mg e 12 mg per g of polymer at 112 h, respectively, vs. a higher loss observed for Nafion, with values of 88 mg per g of polymer, in the same experimental conditions (Fig. lb and 1c). All membranes showed a large decrease to their proton conductivity down to 36 mScm-1, obtained at 60 °C and 80% RH, nearly a third of the proton conductivity observed in similar conditions before their oxidative degradation. The new modified membranes showed higher proton conductivity than the Nafion membrane.