Self-supported iridium integrated leaf-shaped Fe3O4 columnar arrays toward highly efficient oxygen evolution at industrial-grade current density

Abstract

The sluggish kinetics for oxygen evolution reaction (OER) significantly impede the practical applications of electrocatalytic water splitting technology for renewable energy source. The facile design of self-supporting electrocatalysts with high activity and stability for OER catalysis at industrial-grade current density is of paramount significance to mitigate the above bottlenecks. We report herein the construction of iron foam (IF) self-supported Ir-magnetite (Ir-Fe3O4/IF-T-x) electrode via galvanic replacement between IrCl62− ions and Fe2+ in Fe3O4 nanosheet arrays, which is simply synthesized by annealing IF in air and subsequent thermal treatment in reducing atmosphere. Such pre-treatment enables the growth of leaf-like Fe3O4 nanosheet arrays with rich Fe2+ species and oxygen defects, which facilitate the depositing of Ir on the surface of nanosheet arrays and thereby promote the electrochemical OER performance in basic electrolyte. Impressively, the optimized Ir-Fe3O4/IF-400-2 delivers the highest electrocatalytic activity with a low overpotential of 316 mV to obtain industrial-grade current density of 500 mA cm−2 for alkaline OER. Meanwhile, the catalyst still shows good long-term stability after 36 h V-t test at 100 mA cm−2. This study offers a simple and efficient pathway to prepare self-supporting electrode for alkaline OER at industrial-grade current density.