Time Tailoring NiFe₂O₄/Fe-NiS/Ni₃S₂ Heterocatalyst for Industrial-Scale Seawater Splitting

Water electrolysis is a promising approach for hydrogen production. However, achieving cost-effective and durable electrocatalysts at large current densities for seawater splitting remains a significant challenge. This study synthesized a NiFe₂O₄/Fe-NiS/Ni₃S₂ heterostructure on nickel foam (NF) via a simple solvothermal method with varying reaction times. The NiFe₂O₄/Fe-NiS/Ni₃S₂/NF-12h catalyst requires overpotentials of 398 mV for the hydrogen evolution reaction (HER) and 373 mV for the oxygen evolution reaction (OER) to achieve a current density of 1000 mA cm^-2 in an alkaline seawater medium. Notably, the NiFe₂O₄/Fe-NiS/Ni₃S₂/NF-12h (+,-) electrolyzer achieved a cell voltage of 1.92 V at 500 mA cm^-2 and exhibited remarkable stability, maintaining its performance for more than 100 h at 500 mA cm^-2 in an alkaline seawater electrolyte. These findings highlight the critical role of the reaction time in optimizing the morphologies of catalysts. Meanwhile, the synergistic effect of iron doping and interface interaction enhanced the electrocatalytic activity of NiFe₂O₄/Fe-NiS/Ni₃S₂. This work provides a practical strategy for designing high-performance electrocatalysts suitable for industrial-scale seawater electrolysis.