Impact of pH and temperature on the electrochemical and semiconducting properties of zinc in alkaline buffer media

) derived from the impedance data proves this result, which is likely attributed to changes in composition and/or microstructure of the film. In pH 9.8 buffer solution the passivation tendency always decreases with temperature increase. However, in pH 9.2 the system behaves similarly up to 25 °C; afterwards zinc passivation trend was found to re-increase once more. The apparent activation energy for the corrosion process was evaluated and discussed. Analysis of Mott-Schottky plots was found to be suitable for characterizing the semiconductor properties of the naturally deposited barrier layers which are all consistent with the well-known n-type character of the oxide film on zinc. The absence of any evidences for the p-type semiconductive behavior indicates a preponderance of oxygen vacancies and zinc interstitials over metal vacancies. Moreover, Mott-Schottky results demonstrate that the donor concentration increases with either increasing pH or deceasing temperature commensurate with the increasing trends in the passive film thickness.