Evolution of potential distributions during the charging of nano-structured metal oxide films in air as response to sudden voltage application

Using metal oxide film structures, which were originally designed for gas sensing applications, we measured the charging and discharge currents and potential distributions on several metal oxide coatings after the application of an electrical potential against earth. The potential distributions show a specific charging of the surface with oxygen ions through the gas phase. The accumulated charge corresponds to that of the pseudocapacitors. Influence of air humidity has been found to be low, voltaic and temperature dependences of the charge are presented. The activation energy of discharge indicates a weak chemisorption of the charging oxygen species on the metal oxide surface.