An electrochemically engineered layer of γ-NiOOH with FeOOH on nickel foam for durable OER catalysis for anion exchange membrane water electrolysis

Abstract

An efficient and durable oxygen evolution reaction catalyst is essential for the advancement of anion exchange membrane water electrolyzers. Here we report a simple, rapid, and cost-effective two-step electrochemical synthesis of an efficient and durable oxygen evolution reaction catalyst, which can be produced on an industrial scale. In the first step of catalyst preparation, a ≈250 nm thick γ-NiOOH layer was electrochemically developed over nickel foam. Then iron was electrochemically deposited on γ-NiOOH to stabilize the NiOOH species and improve the OER activity. Various material characterization techniques confirmed the presence of a highly OER-active combination of γ-NiOOH and FeOOH at the catalyst surface. The synergism between high valent Ni^3.6+ in γ-NiOOH and Fe³⁺ in FeOOH helps the catalyst to attain 10 mA cm⁻² at 1.47 V with a very low Tafel slope value of 34 mV per decade. The catalyst attained 1 A cm⁻² at 1.65 V in 1 M KOH at 80 °C under real electrolyzer operational conditions. Furthermore, the catalyst exhibits stable OER activity at high current densities under real electrolyzer testing conditions.