An in-situ IR spectroscopic study of the anodic oxide film on cobalt in alkaline solutions

The composition of the oxide film on a cobalt electrode in 1 M and 0.1 M NaOH solutions was investigated using in-situ Fourier transform IR spectroscopy (SNIFTIRS). Co(OH)2 was found to be produced in the active potential region preceding passivation. At higher potentials some of the Co(OH)2 was oxidized to one or several Co(III) oxides which could not be positively identified. Formation of CoO was not detected because it absorbs mainly in a spectral region outside our experimental range.