Metal cations effect of Ni active sites in layered double hydroxides enables efficient anion exchange membrane water...

Anion exchange membrane water electrolysis faces significant challenges due to the kinetically sluggish four-electron oxygen evolution reaction (OER). Layered double hydroxides (LDHs) are active for OER, however, the fundamental relationship between their electronic structure and catalytic performance remains ambiguous. This work investigates the electronic modulation of Ni sites in NiAl-LDH through strategic incorporation of s-block and d-block metal cations. A distinct volcano-shaped thermodynamic correlation emerges between the Ni valence states and OER activity upon metal substitution. Synergistic modification with Co and Fe (CoFeNiAl-LDH) optimally regulates the Ni d-band center position and oxidation states, which facilitates OH^- adsorption/desorption processes at the electrocatalyst-electrolyte interface, and lowers the energy barrier for the rate-determining *O → *OOH transition. When integrated CoFeNiAl-LDH in an anion exchange membrane electrolyzer, it enables stable water splitting at 100 mA cm^-2 with a low cell voltage of 1.68 V. This work establishes a cation engineering paradigm for rational design of high-efficiency electrocatalysts through precise electronic structure manipulation.