Fluorine‐Modulated Hierarchical NiFeCo‐LDHs for Efficient and Stable Bifunctional Water Splitting in Alkaline and Seawater Media

This work synthesized a hierarchical‐structured nickel‐iron‐cobalt layered double hydroxide (NiFeCo‐LDHs) with heterointerfaces via a controllable hydrothermal method. The ternary metal system optimized the charge transport pathways through atomic‐level synergy specifically the multivalent synergy. Furthermore, the high electronegativity of fluorine modulated the electronic conduction kinetics of NiFeCo‐LDHs. Electrochemical testing demonstrated that, Owing to Ni 2+ doping and fluorine atom modulation of LDH interlayer spacing, the NiFeCo‐LDHs exhibited significantly enhanced hydrogen evolution reaction (HER) performance in 1.0 M KOH electrolyte. The HER overpotential is 74.3 mV at a current density of −10 mA cm −2 . As a bifunctional electrode, it required an OER overpotential of only 204.3 mV to achieve 10 mA cm −2 , and its stability remains robust even after 12 h of cycling. Notably, the catalyst maintains impressive performance for both HER and OER in seawater environments.