Dynamic Reconstruction Engineering Enables Dual‐Mechanism Synergy to Break the Activity‐Stability Trade‐Off in Oxygen Evolution Reaction

ABSTRACT A dual‐layer structured catalyst (S‐NiFeO x H y /NiFe) comprising an inner nickel sulfide layer and an outer iron oxide layer was constructed on a nickel‐iron foam through a combined approach of electrochemical treatment and selective hydrothermal sulfidation. This catalyst demonstrates exceptional OER activity and remarkable stability under alkaline conditions, achieving overpotentials as low as 216.6 and 287.0 mV at current densities of 100 and 300 mA cm −2 , respectively, while maintaining stable operation for over 9000 and 7300 h. Using various in situ characterization techniques, the sulfur loss‐triggered dynamic reconstruction process is systematically elucidated, whereby nickel sulfide transforms into highly active NiOOH, while FeOOH undergoes nanoscale refinement and valence elevation, collectively forming an efficient catalytic interface. The reaction proceeds via a synergistic combination of the lattice oxygen mechanism (LOM) and the adsorbate evolution mechanism (AEM), with NiOOH primarily facilitating LOM for high efficiency and FeOOH favoring AEM for excellent stability. This dual‐mechanism coupling significantly enhances both reaction efficiency and durability. The surface iron oxide layer effectively suppresses sulfur dissolution, maintaining a slow and controllable reconstruction cycle that ensures long‐term catalyst stability. This work provides new insights into the design of high‐performance electrocatalysts through dynamic reconstruction and mechanistic synergy strategies.