Harnessing the Li⁺–F⁻ electronic seesaw effect in NiFe-layered double hydroxides for balanced oxygen and hydrogen evolution

NiFe layered double hydroxides (NiFe-LDHs) show considerable promise as electrocatalysts for overall water splitting; however, their performance is often limited by sluggish reaction kinetics. In this study, we demonstrate that Li⁺ and F⁻ dopants impose opposite electronic effects on NiFe-LDH: Li⁺ donates electron density to the metal center and expands the interlayer spacing, thereby facilitating the rapid formation of the active NiOOH phase; conversely, the highly electronegative F⁻ stabilizes high-valent Ni species and promotes reactions involving protons. This antagonistic interplay constitutes a Li⁺–F⁻ electronic seesaw effect; thus, the incorporation of both ions into NiFe-LDH on nickel foam (Li,F-NiFe-LDH/NF) optimizes the electronic structure, resulting in superior oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities with overpotentials of 201 and 104 mV, respectively. In situ Raman spectroscopy confirms the earlier onset of reaction and greater extent of NiOOH formation. This dual-ion doping strategy provides a general route to harnessing electronic seesaw effects for the design of high-performance bifunctional electrocatalysts.