Effects of Humidification on Proton and Electron Conductivity of an Activated Carbon–Nafion Composite Electrode

Abstract

An activated carbon–Nafion composite electrode with dual proton and electron conductivity has been developed, which can be employed for applications for storage of hydrogen electrochemically. Electrochemical impedance spectroscopy was used to measure proton conductivity of the composite electrode. The measured dc resistance was used to calculate electron conductivity of the composite electrode. The effect of humidification on proton and electron conductivity of the composite electrode was studied by varying the level of hydration. The activated carbon used was a common form of activated charcoal powder. As a source of proton-conducting medium within the composite, Nafion-117 solution was employed. Electron conductivities in the range of 0.000177–0.019597 S/cm were recorded, while the proton conductivities were in the range of 0.014775–0.042273 S/cm. It was found that the electron conductivity drops with the increased level of hydration, while proton conductivity goes up.