Unraveling the Dynamic Behavior of Iron-doped Oxidized Cobalt-Nickel Alloy in the Oxygen-Evolution Reaction

Abstract

The oxygen-evolution reaction (OER), which involves water oxidation, is a complex four-electron reaction with a high activation barrier. In this study, an iron-doped oxidized cobalt-nickel alloy is reported as an efficient and stable OER electrocatalyst. The anodized electrode underwent various characterizations, including surface-enhanced Raman spectroscopy (SERS). In situ SERS was utilized to investigate the mechanism of the OER and detect high-valence metal oxides during the OER, where high-valence Ni-(III) and Co-(IV) species were observed. Chronoamperometry experiments show the reduction of Ni-(III) and Co-(IV) ions under open circuit potential (OCP) conditions. Co-(IV) was immediately reduced to Co-(III), whereas Ni-(III) persists even after the addition of Fe ions. OER can potentially occur at active sites composed of Ni, Co, and Fe, depending on their respective potentials. Overall, these findings provide valuable insights into the development of advanced OER catalysts and the underlying mechanism for efficient water splitting toward energy storage.