Ring-disk electrode studies of the open-circuit dissolution of iodine films formed during the anodic oxidation of iodide on platinum

The open-circuit behavior of iodine films formed on platinum by electrooxidation of iodide was studied at rotating disk and rotating ring-disk electrodes. The potential transient and ring current transient at open circuit for c_I^->0.012 M can be explained by assuming: (1) convective-diffusion controlled dissolution of the film; (2) establishment of the I₂+I^-→ I₃^- equilibrium; (3) establishment of the I₂ (solid) →I₂ (solution) equilibrium. The behavior at lower concentrations of c_I^- suggests that convective-diffusion control is absent.