The Behaviour of Polyvinyl Alcohol at the Planar Cd/Cd(OH) sub(2) Electrode Interface

The anodic oxidation of cadmium in alkaline solution was studied using potentiostatic pulse and AC impedance techniques in the presence of a polyvinyl alcohol (PVA) expander. Potential step investigation indicates that there is a change in the reaction mechanism as a result of PVA addition to the electrolyte. This is caused by a change in the active surface area. Impedance measurements reveal a decrease in the charge transfer resistance and an increase in the double layer capacity when PVA is present. The results also confirm that PVA in the electrolyte hinders the cadmium hydroxide film formation and enhances the overall dissolution rate of metallic Cd.