Electrodeposition of hierarchically structured three-dimensional nickel–iron electrodes for efficient oxygen evolution at high current densities

TLDR

Large‑scale industrial water electrolysis demands inexpensive, robust oxygen evolution electrodes capable of delivering current densities above 500 mA cm⁻² at low applied potentials. The study aims to develop such an electrode by electrodepositing amorphous mesoporous nickel–iron composite nanosheets onto macroporous nickel foam. The electrode is fabricated by direct electrodeposition of the composite nanosheets onto the foam substrate. The resulting electrode exhibits high catalytic activity, requiring only 200 mV overpotential to initiate water oxidation, delivers 500 and 1,000 mA cm⁻² at 240 and 270 mV, remains stable under large‑current electrolysis, and is the most efficient alkaline oxygen evolution electrode reported to date.

Abstract

Abstract Large-scale industrial application of electrolytic splitting of water has called for the development of oxygen evolution electrodes that are inexpensive, robust and can deliver large current density (>500 mA cm −2 ) at low applied potentials. Here we show that an efficient oxygen electrode can be developed by electrodepositing amorphous mesoporous nickel–iron composite nanosheets directly onto macroporous nickel foam substrates. The as-prepared oxygen electrode exhibits high catalytic activity towards water oxidation in alkaline solutions, which only requires an overpotential of 200 mV to initiate the reaction, and is capable of delivering current densities of 500 and 1,000 mA cm −2 at overpotentials of 240 and 270 mV, respectively. The electrode also shows prolonged stability against bulk water electrolysis at large current. Collectively, the as-prepared three-dimensional structured electrode is the most efficient oxygen evolution electrode in alkaline electrolytes reported to the best of our knowledge, and can potentially be applied for industrial scale water electrolysis.