States of water in recast Nafion® films

The amount and states of water in a polymer electrolyte significantly affect the material's morphology as well its mechanical transport properties, thus determine performance many important applications such fuel cells, electrolyzers, other electrochemical energy conversion devices. In this study, recast H+-Nafion® films were characterized using attenuated total internal reflection FTIR (ATR-FTIR) spectroscopy before after thermal annealing subsequent rehydration. hydrated determined by analyzing O–H stretching band principle component analysis multivariate curve resolution. It was found that at temperature above glass transition caused hydrogen-bonding networks water-ionic clusters to become restricted, suggesting forms robust matrix confining clusters. evolution film with increasing thermal-annealing confirmed small-angle X-ray scattering (SAXS) CO2 diffusion measurements. Fuel cell tests annealed unannealed Nafion® cathode catalyst layer improved stability when annealed, indicating history is an design parameter device fabrication.