In situ generation of Ni/Fe hydroxide layers by anodic etching of a Ni/Fe film for efficient oxygen evolution reaction

Abstract

Commercial applications of electrolytic water splitting require cost-efficient and active oxygen evolution catalysts. Nickel–iron (NiFe)-based compounds have attracted significant attention as oxygen evolution reaction (OER) catalysts due to their high catalytic activity. We develop a simple and easily controlled method by combining anodic fluoridation and cyclic voltammetry (CV) treatment to convert NiFe alloy to Ni/Fe hydroxide. A cracked layer structure of Ni/Fe hydroxide formed on the surface during the fluoridation of NiFe alloy and the CV process in KOH. The Ni/Fe hydroxide exhibits considerable OER activity with an onset potential of 1.47 V vs. RHE and a Tafel slope of 47 mV dec⁻¹ in 0.1 M KOH. The electrode also shows an acceptable stability in alkaline media. The results indicate that anodic fluoridation and CV treatment are promising methods to form active layer structures of hydroxide on transition metals and their alloys, further increasing the electrocatalytic activity of the catalyst.