Nickel-Iron layered double hydroxide with interlayer distortion induced by site-dependent Mg for anion exchange membrane water electrolysis as anode catalyst.

Nickel‑iron layered double hydroxide (NiFe-LDH) has received widespread attention as the promising non-noble metal catalyst to promote oxygen evolution reaction (OER) for anion exchange membrane water electrolysis (AEMWE). However, the complex valence state conversions of metal sites during catalytic process lead to significant kinetic retardation. In this work, an innovative NiFe-LDH-based core-shell material with minimal Mg incorporation to regulate both interlayer structure and electronic state is presented. The introduction of Mg at optimal sites induces local structural distortions, leading to expanded interlayer spacing that imparts intercalation-like characteristics. In synergy with oxygen vacancies generated by the structural distortion and the electron-pushing effect of Mg, a finely tuned balance is achieved in the redox competition among Ni valence states, which optimizes the reaction kinetics and lowers the energy barrier of the rate-determining step (RDS). Consequently, the overpotential required to reach a current density of 10 mA cm-2 for Mg-NiFe-LDH/NiCo2O4 is 279 mV (228 mV as gas diffusion electrode), which is significantly lower than that of unoptimized materials. Additionally, the water electrolyzer exhibits a low cell voltage of 1.72 V to attain 1 A cm-2. This work presents novel insights for the design of advanced OER electrocatalysts and sustainable hydrogen production technologies.