Post‐Synthetic Bimetallic Assembly of 2D CoFe‐MOF Composite as an Electrocatalyst for the Oxygen Evolution Reaction

ABSTRACT Metal‐organic frameworks (MOFs) are promising oxygen evolution reaction (OER) electrocatalysts, yet their commercial viability is impeded by poor conductivity and stability under alkaline conditions. Herein, a stable CoFe‐MOF composite was synthesized via a post‐synthetic bimetallic assembly strategy, creating uniform Co–Fe coordination sites within a Co‐MOF‐derived framework. The resulting CoFe‐MOF composite possesses hierarchically porous two‐dimensional (2D) nanosheet structure. The composite delivers remarkably enhanced OER performance, achieving a low overpotential of 290 mV at 10 mA cm −2 and a minimal Tafel slope of 31.88 mV dec −1 , significantly outperforming pristine Co‐MOFs and Fe‐MOFs. Systematic density functional theory (DFT) calculations provide profound theoretical support, revealing that the Fe active site (CoFe‐Fe) exhibits an optimal theoretical reaction barrier (Δ G max ) of only 1.67 eV for the rate‐determining step, which is 0.43 eV lower than that of Co‐MOFs (2.1 eV). This superior intrinsic activity can be attributed to the Co–Fe synergistic electronic effect (Fe→O→Co charge transfer), which effectively optimizes intermediate adsorption and enhances metallic character. Moreover, the nanosheet‐stacked structure ensures excellent long‐term operational stability (over 35 h), effectively mitigating structural collapse in strong alkaline electrolytes. This work demonstrates an effective structural regulation and performance enhancement strategy for designing highly stable MOF‐based water‐splitting electrocatalysts.