Continuous-Flow Engineered CoMnFe Layered Double Hydroxides with Electronically Optimized Active Sites for Efficient and Stable Water Oxidation

Oxygen evolution reaction (OER) represents the primary kinetic bottleneck in water electrolysis. Developing non‐precious metal‐based OER catalysts that integrate high activity, robust stability, and low cost remains a critical challenge. Herein, a continuous‐flow synthesis of CoMnFe‐layered double hydroxides (LDHs) is reported that enables superior process control and efficiency over conventional batch methods, as well as extensibility to spinel oxides. The resulting Co2Mn0.5Fe0.5 LDH catalyst achieves a low overpotential of 330 mV at 1 A·cm−2 and maintains superior stability over 200 h at 100 mA·cm−2, significantly outperforming its CoMn‐based counterparts. Mechanistic studies reveal that Fe incorporation promotes Co pre‐oxidation and accelerates surface reconstruction into active (Mn, Fe) doped CoOOH phases during oxygen evolution. First‐principles calculations indicate that Fe substitution optimizes the adsorption/desorption behavior of reaction intermediates and elevates the valence state of Co sites, which thereby reduces the OER energy barrier and enhances the intrinsic activity and stability of the MOOH catalyst.