Tungsten Defect‐Induced Surface Reconstruction of Ce ₂ W ₂ O ₉ Arrays for Enhanced Oxygen Evolution Reaction Performance

Abstract Cerium oxide has emerged as a crucial promoter for regulating the electrocatalytic oxygen evolution reaction (OER) performance of other active components; however, the mechanism underlying its intrinsic activity remains poorly understood. Herein, a novel self‐supported coral‐like Ce 2 W 2 O 9 array is synthesized on carbon cloth using a simple ion‐exchange method. The in situ electrochemical surface reconstruction facilitated the formation of W defects, which effectively altered the local bonding environment of Ce atoms. Based on advanced characterization techniques and theoretical calculations, it is concluded that the optimized Ce centers served as active sites, substantially reducing the energy barrier of the potential‐determining step ( * OOH formation), in turn, facilitating O 2 generation and boosting the intrinsic activity. Consequently, the reconstructed Ce 2 W 2 O 9 electrode exhibited an exceptionally low overpotential of 351 mV at 100 mA cm −2 in 1 m KOH, while maintaining remarkable stability for over 1 000 h at 20 mA cm −2 . This study provides valuable insights into the mechanistic understanding and strategic design of rare‐earth oxide‐based electrocatalysts.