Corrosive engineering assisted in situ construction of an Fe–Ni-based compound for industrial overall water-splitting under large-current density in alkaline freshwater and seawater media

Abstract

As a practical approach for hydrogen generation, electrolysis water-splitting, particularly in seawater, is considered an attractive technique. Herein, an Fe–Ni based compound on a NiFe foam (Fe–Ni–O–N) is in situ engineered via ambient corrosive engineering, following low-temperature nitridation. The as-prepared Fe–Ni–O–N presents a flower-like morphology composed of nanosheets with abundant active sites, large surface area, and rich channels. Moreover, the superhydrophobic surface and porous matrix favor accelerating the mass and charge transfer. Benefiting from the above merits, 1.49 and 1.51 V are required for Fe–Ni–O–N electrocatalyst for OER with low potentials to reach 500 mA cm⁻² in 1 M KOH fresh water and seawater. Moreover, to deliver 500 mA cm⁻², low cell voltages of 1.87 V and 1.90 V are required in 1 M KOH freshwater-splitting and seawater-splitting. For industrial applications, the assembled electrolyzer exhibits remarkable catalytic performances and stabilities under large current densities in freshwater and seawater (60 °C, 6 M KOH).