Anodization of a NiFe Foam: An Efficient and Stable Electrode for Oxygen-Evolution Reaction

Water splitting for hydrogen production is a promising method for storing sustainable energy sources. The oxygen-evolution reaction (OER) through water-oxidation reactions provides electrons for hydrogen production and is a limitation for water splitting. Thus, finding an efficient and stable OER catalyst is critical for water splitting. Herein, a NiFe foam, after harsh anodization at 60 V in a two-electrode system, is reported as an efficient and stable electrocatalyst. The NiFe oxide formed on the NiFe foam's surface was characterized by some methods. These methods show the presence of different NiFe (hydr)oxides such as Ni(OH)2, NiO, and NiO(OH) on the surface of the NiFe foam. For the prepared electrode in the KOH solution (1.0 M), the overpotential for the onset of the OER is 220 mV. The overpotentials for the activities of 1, 10, and 100 mA/cm2 are observed at 290, 346, and 500 mV, respectively. A stable NiFe-oxide-based layer protects the bare foam from further oxidation, resulting in a stable electrocatalyst for the OER.