Molecular Design of 1D Iron‐Based MOF for High‐Performance Oxygen Evolution Reaction

ABSTRACT We designed a series of one‐dimensional metal–organic frameworks (MOFs) on nickel‐iron foam (NiFe foam) surfaces via molecular tailoring and assembly to achieve enhanced electrocatalytic performance. Molecular tailoring was accomplished by introducing secondary metal ions (Ni or CoNi) and substituting bulky ligands in [Fe(Htpim) 2 (HOBA) 2 ·2(H 2 O)] n ( Fe‐MOF‐L ; Htpim = 2,4,5‐tri(4‐pyridyl)‐imidazole; H 2 OBA = 4,4′‐oxybisbenzoic acid) with compact acetate ligands, yielding MFe‐MOF‐L (M═Ni or CoNi) and [Fe(Htpim) 2 (CH 3 COO) 2 ] n ( Fe‐MOF) . The morphology of MOFs was tuned by varying the NiFe foam thickness and controlling reaction conditions. Synergistic etching of the substrate coupled with in situ generation of compact CH 3 COO − ligands enabled the formation of ultrafine hierarchical nanostructures. The Fe‐MOF@4 mm NiFe foam catalyst exhibited ultralow overpotentials of 194, 201, and 208 mV at 100, 500, and 1000 mA cm −2 , respectively. Moreover, the catalyst demonstrated excellent stability, sustaining consistent activity for 180 h in 1.0 M KOH and 150 h in alkaline natural seawater at 1000 mA cm −2 , with negligible degradation. Both experimental analyses and theoretical calculations revealed that ligand exchange to introduce compact CH 3 COO − ligands in Fe‐MOF represents the most efficient approach to achieve milestone performance in MOF‐based oxygen evolution reaction (OER) electrocatalysis.