Refining anodic and cathodic dissolution mechanisms: combined AESEC-EIS applied to Al-Zn pure phase in alkaline solution

Abstract

AbstractIn this work, the use of atomic emission spectroelectrochemistry (AESEC) coupled to electrochemical impedance spectroscopy (EIS) is presented as a method of revealing dissolution mechanisms. To illustrate the method, the dissolution kinetics of Al cations from an Al-Zn pure phase (Zn-68 wt.% Al) was investigated in an alkaline solution. In the cathodic potential domain, a nearly direct formation of dissolved Al3+ was observed, while in the anodic potential domain the Al dissolution occurred by migration across a ZnO/Zn(OH)2 film. It was demonstrated that this methodology can be applied to a nonstationary system during a potentiostatic experiment for a lower Al content phase (Zn-22 wt.% Al). The nature of the charge transfer mechanisms depended on the applied potential and could be identified by comparing the direct current and alternating current faradaic yield using AESEC-EIS.