Corrosion-Guided Surface Engineering of Permalloy for Efficient Alkaline Oxygen Evolution Reaction

The production of H₂ via water electrolysis is limited by the kinetically sluggish oxygen evolution reaction (OER) that occurs on the anode of water electrolysis. In alkaline water electrolysis, OER is catalyzed equally well by non-noble metals-based catalysts. In this study, we report one such advanced OER electrocatalyst developed by an unconventional electrochemical anodization in acid from a readily available, abundant, and cheap permalloy (Ni_0.8Fe_0.2). The unconventionally activated (in sulfuric acid (pH 0)) commercially purchased Ni_0.8Fe_0.2 sheets delivered 10 mA cm^-2 at 264 mV in 1.0 M KOH for OER while maintaining an impressive 95% activity retention after 12 h. All this while exhibiting smaller Tafel slope (38 mV dec^-1) testifying ultrafast OER kinetics. Our analysis revealed that the unconventional acid activation led to the increased surface roughness of the permalloy substrate that featured intrinsically OER active NiFeOOH nanostructures on the surface. Such intentional design converted the otherwise moderately active permalloy into a high-performance OER electrocatalyst. This study can also be extended to other prospective substrates for similar electrochemical activation and their subsequent use in OER and in other energy conversion electrocatalytic reactions.