A nanoporous nickel–iron alloy seamlessly anchored into hierarchical porous nickel for efficient and extremely stable water splitting

Abstract

The development of a robust, low-cost electrode for electrochemical water splitting is a challenging, but essential task for realizing hydrogen production under industrial conditions. Here, we seamlessly anchor nanoporous nickel–iron into a hierarchical porous nickel foam (npNi–Fe/HPNF) by a designed gaseous oxidation–reduction engineering for a commercial nickel foam. The three-dimensional hierarchical porous structure considerably enhances the specific surface area of the electrode, yielding abundant electrocatalytic sites that promote the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Moreover, owing to its mechanically robust, seamlessly anchored architecture, and remarkable superhydrophilicity/superaerophobicity, the electrolyzer composed of self-standing npNi–Fe/HPNF and its electro-activation derivative displays a current density of 10 mA cm−2 at 1.54 V, ultralong durability of more than 2000 h at 500 mA cm−2 in a 1 M KOH electrolyte, and high performance of 2 V at 1 A cm−2 in a quasi-industrial environment (5 M KOH and 70 °C), outperforming most alkaline electrolyzers based on state-of-the-art electrodes. Exceptional electrochemical performance and the ability to be prepared at a large scale (2500 cm2) make npNi–Fe/HPNF a promising candidate for industrial water splitting applications.