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

Abstract

Design of low-cost and highly efficient electrodes for oxygen evolution is highly desirable for bulk water electrolysis associated with several conversion and storage of the renewable energies. 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 200mAcm−2, the 3D Ni0.70Fe0.30OOH/CFC electrode in 1.0M KOH only requires overpotentials of 200 and 205mV, respectively, outperforming the commercial IrO2 catalyst and all previously reported Ni–Fe catalysts. Furthermore, the Ni0.70Fe0.30OOH/CFC electrode can continuously operate at >350mAcm−2 over 100hours with a negligible current loss in 1.0M 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.