Time Tailoring NiFeO/Fe-NiS/NiS 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 NiFeO/Fe-NiS/NiS heterostructure on nickel foam (NF) via a simple solvothermal method with varying reaction times. The NiFeO/Fe-NiS/NiS/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 in an alkaline seawater medium. Notably, the NiFeO/Fe-NiS/NiS/NF-12h (+,-) electrolyzer achieved a cell voltage of 1.92 V at 500 mA cm and exhibited remarkable stability, maintaining its performance for more than 100 h at 500 mA cm 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 NiFeO/Fe-NiS/NiS. This work provides a practical strategy for designing high-performance electrocatalysts suitable for industrial-scale seawater electrolysis.