Potential-Dependent Adsorption and Desorption of Perfluorosulfonated Ionomer on a Platinum Electrode Surface Probed by Electrochemical Quartz Crystal Microbalance and Atomic Force Microscopy

Potential-dependent adsorption/desorption behavior of perfluorosulfonated ionomer (PFSI) on a platinum electrode was investigated by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM), and electrochemical atomic force microscope (EC-AFM) in a Nafion, that is, PFSI, dispersed aqueous solution without any other electrolyte. PFSI adsorbed on the platinum surface in the potential region between 0.1 and 0.8 V versus Ag/AgCl and desorbed from the surface at 1.1 V where place-exchanged Pt oxide was formed. Once platinum oxide was reduced, PFSI readsorbed on the surface. These processes took place reversibly.