Accelerating the reconstruction of NiFe via molybdate anchoring for chloride-tolerant and stable seawater splitting

Suppressing the chlorine evolution reaction and mitigating chloride-induced corrosion remain central challenges for seawater electrolysis. Herein, this paper proposes an anion-accelerated directional catalyst reconstruction strategy. Guided by density functional theory (DFT) screening among a series of oxyanions, MoO₄^2- is identified as the optimal species to tailor the NiFe surface. MoO₄^2- not only drives the rapid and controlled reconstruction of NiFe into highly corrosion-resistant NiFe layered double hydroxide (LDH) but also optimizes the surface electronic structure, thereby lowering the oxygen evolution reaction (OER) energy barrier and enhancing intrinsic activity. The resulting MoO₄^2-/NiFe LDH delivers an overpotential of only 324.85 mV at 100 mA·cm^-2 and exhibits extraordinary durability in natural seawater, operating stably at 500 mA·cm^-2 for over 1000 h. Mechanistic investigations reveal a dual protection mechanism: surface-anchored MoO₄^2- stabilizes Fe sites while promoting the formation of high-valence Ni active species, and detached MoO₄^2- confined within the electric double layer functions as an ion sieve, selectively repelling Cl^- and reinforcing corrosion resistance. When integrated with commercial platinum on carbon (Pt/C) in an anion exchange membrane (AEM) electrolyzer, the system achieves a cell voltage of only 1.96 V at 500 mA·cm^-2, stable operation for 200 h, and a remarkably low energy consumption of 4.65 kW·h/Nm³ H₂, outperforming conventional RuO₂-based systems. The paradigm of anion-accelerated reconstruction is established, endowing earth abundant catalysts with excellent seawater corrosion resistance and bringing practical industrial scale hydrogen production from seawater electrolysis one step closer.