Revealing Local Coordination-Modulated Oxygen Evolution Reactivity in High-Entropy Layered Double Hydroxides

Layered double hydroxides (LDHs) are promising electrocatalysts for the oxygen evolution reaction (OER), but their sluggish kinetics and structural instability under industrial operating conditions severely limit their practical applications. Here, we demonstrate that high-entropy NiCoZnFeCr-LDHs (HE-LDHs), in which the Fe³⁺: Cr³⁺ ratio is precisely controlled, can modulate redox behavior, local coordination, and catalytic activity. NiCoZnFe_0.8Cr_0.2-LDH achieves superior OER performance with an overpotential of 199 mV at 10 mA cm^-2 with a Tafel slope of 37 mV dec^-1, while maintaining outstanding durability at 1 A cm^-2 over 1200 h, among the best reported for non-noble LDH-based catalysts. Operando spectroscopic analyses reveal that compositional variations tune the oxidation behavior of metals and the local phase evolution, including the reconstruction of Ni species into γ-NiOOH during OER, together with a particularly significant alteration in Zn local coordination from octahedral to tetrahedral. Density functional theory calculations support that the tetrahedral Zn induces electron localization on adjacent oxygen sites, enabling internal hydrogen bonding that substantially lowers the energy barriers of the potential-determining steps and stabilizes reaction intermediates in the lattice oxygen-mediated mechanism (LOM). This work provides fundamental insights into the structure-activity relationships by composition tuning in multicomponent OER catalysts.