Oxygen-evolution reaction by nickel/nickel oxide interface in the presence of ferrate(VI).

In this study, we investigate the effect of KFeO, as a new and soluble Fe salt at alkaline conditions, on oxygen-evolution reaction (OER) of Ni oxide. Both oxidation and reduction peaks for Ni in the presence and absence of Fe are linearly changed by (scan rate). Immediately after the interaction of [FeO] with the surface of the electrode, a significant increase in OER is observed. This could be indicative of the fact that either the [FeO] on the surface of Ni oxide is directly involved in OER, or, it is important to activate Ni oxide toward OER. Due to the change in the Ni(II)/(III) peak, it is hypothesized that Fe impurity in KOH or electrochemical cell has different effects at the potential range. At low potential, [FeO] is reduced on the surface of the electrode, and thus, is significantly adsorbed on the electrode. Finally, oxygen-evolution measurements of KFeO and NiO are investigated under chemical conditions. KFeO is not stable in the presence of Ni(II) oxide, and OER is observed in a KOH solution (pH ≈ 13).