IN-SITU XANES STUDY OF GALVANOSTATIC REDUCTION OF THE PASSIVE FILM ON IRON

In situ XANES (x-ray absorption near-edge structure) was used to study galvanostatic reduction of the passive film on iron. In a berate buffer, the film appears to be removed in a layer-by-layer fashion by reductive dissolution during the first potential arrest. A burst of dissolution takes place at the end of the arrest for slow reduction rates. During the course of reduction, the remaining film shows a composition change from ferric oxide toward Fe3O4. This may indicate that the film has an inner layer of Fe3O4. Galvanostatic reduction of the passive film grown on iron in 0.1M KOH leads to complete reduction of the passive film to ferrous oxide or hydroxide without any detectable dissolution.