Formation and reduction of films on amalgamated and non-amalgamated zinc electrodes in alkaline solutions

Abstract

The formation of surface films on amalgamated and non-amalgamated zinc electrodes in KOH electrolyte has been investigated by linear sweep voltammetry and by using a rotating disc electrode and a ring disc electrode. The results obtained indicate that such films are formed by an “adsorption” as opposed to a “dissolution-precipitation model”. In addition, the cathodic behaviour of both amalgamated and non-amalgamated zinc electrodes subsequent to an anodic oxidation has been studied. For unamalgamated zinc electrodes in quiescent solutions and for cathodic sweeps commenced in the potential region of zinc passivity, two distinct reduction processes may be distinguished in addition to a third which arises from the reduction of zincate species dissolved in the solution. The former reduction processes arise from the reduction of two different types of surface films present on non-amalgamated electrodes following reactivation from the passive state. This behaviour is compared to that of similarly treated amalgamated electrodes where only one reduction process is observed under similar experimental conditions.