Use of Raman Spectroscopy and Rotating Split Ring Disk Electrode for Identification of Surface Layers on Iron in 1M NaOH

In situ Raman spectroscopy and rotating split‐ring disk electrode were used to identify products formed on iron in at 22°C at various peaks of cyclic voltammograms. The peak at the most active potential of the cathodic reverse sweep has been ascribed to the reduction of to Fe 2+ species: this peak suggested that started to form at the first peak of anodic sweep and that it built up at nobler potentials. The Raman spectroscopy has revealed the formation of in the wide range of potentials, of and/or at peak III of anodic sweep, and of after prolonged polarization at a potential of 0.27 V (SCE). Rapid cycling or long exposure resulted in the formation of and . It is suggested that the passivating film on iron in is composed of an inner layer and of an outer layer containing other products.