Towards the understanding of the mechanism of dc protonic conduction in graphene oxide

Abstract

It is found the dependence of the graphene oxide dc electrical conduction vs. temperature at fixed air humidity levels (under the laboratory conditions) to be nonmonotonic with a pronounced maximum. The increasing of the conduction while the temperature drops corresponds to the protonic concentration increase due to water molecules adsorption as the result of condensation (chilled mirror effect). At this condensation process, the dew point temperature can be determined as the temperature of the fastest adsorption rate of water molecules (and the protonic conduction fastest increase vs. temperature). At some temperatures, either at 0 °C under atmospheric pressure, when the adsorbed water turns into ice, or at the dew point at T < 0 °C, at further temperature drop the protonic conductivity suddenly starts to exponentially decrease via the Arrhenius-type dependence with the activation energy of ≈ 0.7 eV.