Cathodic Potential Oscillations of Sn(II) Reduction and Hydrogen Evolution in Acid Stannous Sulfate Solutions

Abstract

Cathodic potential oscillations of Sn(II) reduction and hydrogen evolution in acid stannous sulfate solutions were investigated by cyclic voltammetry under galvanostatic conditions and chronopotentiometry. The potential oscillations are observed when the applied current density is above the limiting value, and they are observed only at low current scan rates and at constant current density. In the absence of gelatin, damped potential oscillations are evident. This is attributed to a dendritic growth, which increases the surface area and reduces the current density below the limiting value. Sustained potential oscillation can be achieved with gelatin, where a smooth deposit is expected due to an inhibitory effect and∕or absorption of gelatin on the cathode surface. It has been found that gelatin has the effect of extending the lifespan of the potential oscillations. In order to have sustained potential oscillations, the deposits on the cathode should be smooth so that the effective current density remains higher than the limiting value.