THE STABILITY OF HYDROUS OXIDE-FILMS ON GOLD

The stability of hydrous oxide films produced on gold by anodizing at 2.2 V (RHE) in acid solution was investigated as a function of holding potential in both acid and base. In contrast to platinum, whose behaviour will be described in more detail later, the oxide film on gold was more stable, i.e. more resistant to reduction, in solutions of high pH. This was attributed to a persistent anionic character in the case of hydrous gold oxide. Other factors relevant to the reactivity of such films, e.g. the presence of an inner layer of compact oxide and the heterogeneous character of the hydrous oxide deposit, were also considered briefly. A remarkable coincidence was noted between the minor voltammetric peaks observed earlier for clean polycrystalline gold in base and the much larger peaks observed here for hydrous oxide reduction in the same system: the peak maximum potential values for these two significantly different conditions were virtually the same. © 1990.