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

- 3D self-supported Ni1-x-FexOOH/carbon fiber cloth (CFC) electrodes are synthesized.
- The electrodes exhibit remarkably enhanced OER activities as x = 0.30.
- The self-supported electrode requires an overpotential of 205 mV at 200 mA cm−2.
- The electrode can operate stably at >350 mA cm−2 over 100 hours.
- The OER performance of the electrode outperforms the commercial IrO2 catalyst.

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 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 IrO2 catalyst and all previously reported Ni-Fe catalysts. Furthermore, the Ni0.70Fe0.30OOH/CFC electrode can continuously operate at >350 mA cm−2 over 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.

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