Micro/Nanostructured Electrode with Fast Reaction-Transport Nanochannels to Enhance Water Electrolysis of the NiFe Alloy at Large Current Density

The practical application of water splitting is plagued by sluggish reaction kinetics and slow gas bubble release, both of which critically govern mass transfer and energy efficiency in high current densities. Herein, we reported a hierarchical NiFe electrode with fast transport micro/nanostructure, where the well-oriented macroscopic reaction channels enabled large-scale fast mass transfer and bubble release, while the interconnected microscopic nanoporous channels reduced the tortuosity of reactant transport to the active sites and enlarged the three-phase boundary contact area. This tunable micro/nanostructure endowed the electrode with a large active surface area, optimal porosity, and regulated surface wettability. The as prepared micro/nanostructured NiFe electrode exhibited a low oxygen evolution reaction (OER) overpotential of 270 mV at 1000 mA cm –2 with a Tafel slope of 44.04 mV dec –1 . An alkaline water electrolyzer assembled with a (+) NP-NiFe||Pt/C@NF (Nickel Foam) (−) electrode configuration achieved a current density of 1000 mA cm –2 at a low cell voltage of 1.7 V. Benefiting from its monolithic architecture that integrates abundant active sites without relying on additional substrates, the electrode retained long-term durability over 100 h at 1000 mA cm –2 . Furthermore, an anion exchange membrane water electrolyzer (AEMWE) reached 1000 mA cm –2 at cell voltage of 2.06 V under industrial operating conditions.