The anodic dissolution of zinc in alkaline solutions

Abstract

The anodic dissolution of zinc in sodium hydroxide solutions (3×10−2−2 M)has been studied using rotating disc electrodes. The dissolution of zinc in both the active and passive branches occurs with simultaneous zinc deposition. The deposition reactions is first order in zincate. In the active branch the anodic Tafel slope is 42±5 mV/decade and the cathodic Tafel slope 105±10 mV/decade, after diffusion effects are eliminated. Passivity is due to the formation of an anodic phase monolayer on the electrode surface, which has a reversible potential ≈ 100 mV more anodic than the Zn/ZnO electrode.