Current oscillations during potentiostatic anodization of tin in alkaline electrolytes

This paper reports a phenomenon of spontaneous periodical current oscillation during electrochemical anodization of tin in alkaline electrolytes. Such phenomenon has been reported in the literature. Attempts have been made to explain this phenomenon on the basis of oxide film lift-off and electrolyte diffusion. This investigation demonstrates that the current oscillation is caused by oxygen generation and release on the tin anode, causing periodic redistribution of ion concentration in the electrolyte. The analysis also enables determination of the contributions of the two anodic reactions of Sn oxidation and oxygen generation to the total anodic current.

► Anodization of Sn in NaOH solution forms nanoporous SnO2.
► Oxygen formation occurs concurrently at the anode.
► Repeated formation and release of O2 bubbles near the anode causes periodic current oscillation.
► Relative contributions of Sn oxidation and O2 formation to the anodic current are 49% and 51%, respectively.