Proton Transport Property in Supported Nafion Nanothin Films by Electrochemical Impedance Spectroscopy

TheprotontransportpropertyofNafionnanothinfilms (4‐300nm)hasbeeninvestigatedbyelectrochemical impedancespectroscopy (EIS)usinginterdigitatedarray(IDA)ofgoldelectrodesonSiO2 substrate.Theprotonconductivityhasbeeninvestigatedasafunction of film drying/heating protocol, relative humidity, temperature and film thickness. It is found that the film treatment protocol makes a difference in film transport property. Ultimately, the proton conductivity and capacitance of the Nafion nanothin film is thicknessdependent,wheretheformerdecreased andthelatterincreasedexponentiallywithdecreasingfilmthickness.Moreover,theactivation energy increased exponentially with decreasing film thickness. The proton conductivity of the thin films of Nafion is significantly lower than that of the membrane counterpart regardless of the thickness, which is consistent with the high activation energy found in the thin films. These differences are likely related to the polymer confinement and morphological differences between the thin films and the freestanding membrane. © The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any