Unexpected Resilience of NiFe Catalysts for the Alkaline Oxygen Evolution Reaction

Abstract

NiFe catalysts have emerged as promising low-cost alternatives to Ir-or Ru-based anodes for water splitting. Despite their potential, their widespread adoption in commercial alkaline electrolyzers is currently hindered by instability and rapid deactivation under real operating conditions. In this study, we investigate the behavior of NiFe (90/10% at.) thin film (∼35 nm) electrodes fabricated by supersonic cluster beam deposition as electrocatalysts for the oxygen evolution reaction in alkaline media during prolonged electrochemical activity. In particular, we observed that an exfoliation process occurred, leading to the detachment and dissolution of most (∼99%) of the catalyst nanoparticles (NPs) from the electrode surface into the electrolyte. However, upon multiple potential sweeps, a partial NP redeposition occurred. Importantly, we demonstrate the establishment of an equilibrium between the dissolution and readsorption of catalyst NPs from/to the electrode surface, thereby sustaining significant residual catalytic activity.