On the selection of the most probable mechanism of the Cd(II) reduction at mercury from 1 M KF solution

Abstract

A faradaic impedance study has been made of the reduction of Cd(II) ions from a 1 M KF base electrolyte at the DME. It could be shown that only the Cd(II) present in the solution and the end product, viz. Cd(Hg), are the diffusing partmles and that intermediates are present only at the interface. From the analysis of the impedance data it followed that at the interface the Cd(II) species is first subject to a heterogeneous chemical transfer and thereafter is reduced according to two discrete one-electron transfers, both obeying the Butler--Volmer equation. The kinetm parameters of the steps are reported. A number of other conceivable mechanisms were considered, but fortunately they all either could be defimtely ruled out or were found to be less acceptable.