Electronic modulation in a defect-rich high-entropy NiCoFeCu LDH enables accelerated oxygen evolution

Accelerating the oxygen evolution reaction (OER) is critical for efficient alkaline water electrolysis in green hydrogen production. Rational regulation of the electronic structure of transition metal (oxy)hydroxides offers a vital route to enhance their OER kinetics under alkaline conditions. Herein, we reported a defect-rich high-entropy layered double hydroxide, D-NiCoFeCu-LDH, constructed via a sequential electrodeposition–electrochemical etching strategy. Selective chromium leaching reconstructs a homogeneous Ni–Co–Fe–Cu high-entropy matrix while introducing abundant vacancies and lattice distortion. Structural characterization confirms uniform elemental distribution and defect-enriched nanosheet arrays, whereas X-ray photoelectron spectroscopy (XPS) analysis reveals pronounced electronic redistribution, manifested by increased high-valence Ni³⁺/Co³⁺ species and positive binding energy shifts. We proposed that highly dispersed Cu⁺/Cu²⁺ species act as electronic modulators, withdrawing electron density from neighboring Ni, Co, and Fe centers, while lattice distortion further promotes electronic reconfiguration. Electrochemical measurements demonstrated enhanced intrinsic activity and accelerated charge-transfer kinetics compared to quaternary counterparts. Importantly, in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) directly verified facilitated ^*OOH intermediate formation at lower overpotential, establishing a molecular-level link between electronic modulation and improved OER kinetics. In this work, we provide mechanistic insight into how synergistic high-entropy regulation and defect engineering cooperatively enhance intrinsic catalytic activity, offering a framework for designing durable, high-performance OER electrocatalysts.