In the regeneration of MnO4− from MnO42− on a nickel electrode, the oxidation of MnO42− into MnO4− occurs via two-step reactions: Ni(OH)2 + OH-⇌NiOOH + H2O + e NiOOH + MnO 2 - 4 + H 2 O → Ni(OH) 2 + MnO - 4 + OH - Although the efficiencies of both conversion and current of a nickel electrode were less than those of a platinum electrode, a significant improvement was achieved for a nickel electrode when it was pretreated with KOH solution (1 M) for 30 min.
