W‐Mediated Valence‐State Modulation Coupled With Dynamic Fe Reconstruction Drives Stable Oxygen Evolution at 2 A cm −2

Abstract

Electron‐transfer‐regulated interfacial reconstruction has emerged as a defining feature of alkaline oxygen evolution electrocatalysis, yet its mechanistic origin under industrial‐level current densities remains poorly understood. Here, we design a self‐supported W─FeOOH/WO x nanosheet array, in which interfacial electronic modulation stabilizes Fe‐driven reconstruction while governing catalytic activity and durability. Operando X‐ray photoelectron spectroscopy and Raman spectroscopy, together with synchrotron X‐ray absorption spectroscopy, reveal that the W─Fe heterointerface triggers a cooperative reconstruction process, leading to the formation of a Fe/Ni oxyhydroxide‐rich reconstructed layer coupled with residual WO x domains. X‐ray absorption spectroscopy further the evolution of Fe toward FeOOH‐like coordination environments while preserving the local WO x framework. Density functional theory calculations reveal that the reconstructed heterointerface shifts the Fe d‐band center upward and induces adsorption‐induced charge redistribution at W sites (Δ ≈ 0.223 e − upon OOH * adsorption), thereby lowering the energy barrier of the rate‐determining * OOH → O 2 step to 1.87 eV. Consequently, the catalyst achieves 1000 and 2000 mA cm −2 at low overpotentials of 300 and 340 mV, respectively, and sustains stable operation for 250 h at 2000 mA cm −2 with a decay rate of 0.08 mV h −1 . This work establishes a design principle for stabilizing dynamic reconstruction at ampere‐level current densities.