Fluoride‐Engineered Electrolyte for Highly Stable and Efficient Alkaline Seawater Electrolysis at 2 A cm −2

Abstract Seawater electrolysis offers an energy‐efficient route for hydrogen production while alleviating freshwater scarcity. However, the presence of Cl − in seawater compromises anode activity and induces severe corrosion, requiring constructing complex electrode architectures that hinder large‐scale application. In this work, we demonstrate that incorporating F − as an electrolyte additive significantly enhances the performance of NiFe layered double hydroxide (NiFe‐LDH) anodes. Upon optimizing the F − concentration, benchmark NiFe‐LDH showed the lower overpotential than that of the F − ‐free system, and achieved stable operation at 2 A cm −2 for 1000 h in seawater electrolyte, representing an approximately 500‐fold improvement over the control set of experiment. The consistency between spectroscopic characterization and multi‐scale simulation results revealed that F − , by virtue of its high electronegativity and charge density, modulates the electronic environment of Ni and Fe sites, enhances the adsorption of OH − , and thereby improves OER activity. Moreover, the introduction of F − increases free water content and modulates the hydrogen bond network to promote OH − transportation while repelling Cl − at the electrode‐electrolyte interface by polarizing the O─H bonds of water molecules on NiFe‐LDH surface. This straightforward electrolyte engineering strategy provides a practical and scalable solution for seawater electrolysis.