Electrochemical Behavior of IrO2 Electrodes in the Anodic Electrodeposition of MnO2

The electrochemical behavior of IrO2 electrodes in a MnSO4 plating solution and in a H2SO4 solution at different temperatures was investigated by polarity curve and cyclic voltammetry methods. The anodic electrode deposition was carried out at different current densities according to the polarity curve obtained in the bath and the deposition velocity was measured. The results show that the anodic electrode deposition reactions and the O-2 production reaction on the IrO2 electrode in the bath occur simultaneously and the former reaction obviously restrains O-2 production. The process of MnO2 electrodeposition onto IrO2 is complicated and a Mn3+ intermediate product is produced, which can be oxidized to Mn4+ during the electrode deposition. Mn3+ is hydrolyzed at the same time as the oxidation and its hydrolysate desorbs, which causes an obvious reduction in current efficiency for the MnO2 anodic electrodeposition. A potential range exists for the MnO2 anodic electrode deposition and we also found a maximum value for the deposition velocity within the potential range.