The Morphology Transition Phenomenon in Nafion thin film/ Platinum Interface

Abstract

Improving oxygen reduction reaction (ORR) activity of cathode catalyst is required for wide spread of polymer electrolyte fuel cells. Because ORR occurs at the interface between cathode catalyst and ionomer (Nafion), understanding the structure of Nafion on the cathode catalyst is important to design reaction field with high activity. The morphology of the Nafion on the cathode is strongly influenced by humidity, thickness, annealing treatment and so on. The proton conductivity of Nafion increases with humidification, and the change degree depends on the thickness of Nafion. However, the correlation between morphology and proton conductivity of the Nafion on the cathode have not still been clearly understood. In this study, we examined the correlation between morphology and proton conductivity under humidity of Nafion thin-film with annealing treatment via grazing incidence small angle X-ray scattering (GISAXS) and electrochemical impedance spectroscopy.