Effect of Plating Variables on Oxygen Evolution Reaction of Ni–Zn–Fe Electrodes for Alkaline Water Electrolysis

In this study, we investigated the oxygen evolution reaction (OER) characteristics of Ni–Zn–Fe electrodes by varying plating current density and Ni:Fe ratio in a plating bath. The activity of the OER increased up to the plating current density of 160 mA/cm2, as the Fe content of the deposited electrode increased and electrochemical surface area (ECSA) increased after Zn dealloying. However, for the plated electrode with higher than 160 mA/cm2 of current density, the change in composition caused by underpotential deposition led to decreased activity due to decreasing Fe content and diminishing Zn dealloying. Moreover, when the Ni:Fe ratio in the plating bath was varied, outstanding OER activity was observed at Ni:Fe = 2:1. When the Fe content of the bath increased beyond this ratio, Fe could not restrain Ni oxidation and formed Fe oxides in OER reaction, and oxygen vacancy decreased. These caused a degradation of the OER activity.