Study of Pt Electrode/Nafion Ionomer Interface in HClO[sub 4] by In Situ Surface-Enhanced FTIR Spectroscopy

Pt electrode/Nafion interface has been characterized in aqueous solutions using surface-enhanced infrared absorption spectroscopy (SEIRAS) with the aim of investigating the structure of the interface which plays a crucial role in the performance of polymer electrolyte fuel cells (PEFCs). A potential dependent band was found around and assigned to the symmetric vibration of the – groups of the ionomer membrane. Electric field driven orientation/adsorption of the ionomer membrane at the interface was suggested from the potential dependence of the band intensities of – groups. It was inferred that the – groups act like counterions at the Pt/ionomer interface to form the electric double layer.