Dimensional Reduction and Electronic Modulation of 3D MOFs to Ultrathin 2D MOF Electrocatalysts for Enhanced Oxygen Evolution

ABSTRACT The synthesis of two‐dimensional metal–organic frameworks (2D MOFs) from non‐layered three‐dimensional (3D) precursors remains a formidable challenge. Herein, we report a dimensional reduction strategy to transform 3D zeolitic imidazolate framework‐67 (ZIF‐67) into ultrathin 2D MOF nanoribbons. This process is mediated by the controlled formation of a yolk‐shell ZIF‐67@CoNi layered double hydroxide (LDH) intermediate, which undergoes a ligand‐exchange‐induced recrystallization. By modulating the organic linker with ─NH 2 (electron‐donating) and ─NO 2 (electron‐withdrawing) groups, we achieve precise control over the resulting MOF's morphology and the electronic structure of its metal centers. The electron‐rich 2D CoNi NH 2 ─BDC MOF exhibits exceptional oxygen evolution reaction (OER) performance, achieving an overpotential of 288 mV at 10 mA cm −2 and outstanding stability for over 264 h, surpassing commercial RuO 2 . This work provides a generalizable approach for converting 3D MOFs into 2D MOFs and unveils the critical role of morphological structure and linker electronics in dictating electrocatalytic efficacy.