Highly stable three-dimensional nickel–iron oxyhydroxide catalysts for oxygen evolution reaction at high current densities

Mixed Ni–Fe catalysts have showed excellent activities towards oxygen evolution reaction (OER), however, the long-term stability at high current densities has not been well-documented. Here we fabricate three-dimensional (3D) self-supported Ni1-x-FexOOH/carbon fiber cloth (CFC) electrodes for highly efficient oxygen evolution through in situ electrochemical activation of the corresponding 3D Ni1-x-FexS/CFC precursors. The activated Ni–Fe electrodes exhibit remarkably enhanced OER activities compared to the pure Ni and Fe catalysts and the highest OER activity is achieved as x = 0.30. To drive current densities of 100 and 200 mA cm−2, the 3D Ni0.70Fe0.30OOH/CFC electrode in 1.0 M KOH only requires overpotentials of 200 and 205 mV, respectively, outperforming the commercial IrO2catalyst and all previously reported Ni–Fe catalysts. Furthermore, the Ni0.70Fe0.30OOH/CFC electrode can continuously operate at >350 mA cm−2over 100 hours with a negligible current loss in 1.0 M KOH. Such excellent activity and robust long-term stability at high current density demonstrate that the 3D Ni–Fe catalysts can applied in industry for large-scale oxygen production.