Refining anodic and cathodic dissolution mechanisms: combined AESEC-EIS applied to Al-Zn pure phase in alkaline solution
Junsoo Han, Vincent Vivier, Kévin Ogle
Abstract
Abstract In 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 Al 3+ 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.