Ligand Modulation in Metal–Organic Frameworks Derived Regenerable Oxygen Evolution Electrocatalysts

Metal-organic frameworks (MOFs) are emerging as promising pre-catalysts for the oxygen evolution reaction (OER) in water electrolysis. However, the coordination chemistry of MOF ligands in reconstructed species remains poorly understood, particularly regarding how ligand modulation influences the electronic configurations of catalytic sites. In this study, we present the synthesis of an α-FeOOH coated Ni-catecholate MOF composite (FeOOH@Ni-CAT), which transforms into a ligand-coordinated γ-NiFeOOH active species during OER. Notably, this active species can revert to its stable α-phase counterpart, exhibiting an "easy-to-regenerate" characteristic. Theoretical calculations demonstrate that the ligand significantly enhances the adsorption energies of oxygenic intermediates involved in the OER, while also modulating electronic structures by strengthening bonding states and promoting electron delocalization between active sites and intermediates. As a result, the FeOOH@Ni-CAT pre-catalyst exhibits exceptional OER performance, achieving an ultralow overpotential of 180 mV at 10 mA cm^-2 and impressive durability over 384 h (16 days), leveraging the regenerable property. This work advances the understanding of high-performance MOF-based pre-catalysts by elucidating the fundamental mechanisms of structural reconstruction during OER and highlighting the role of ligand modulation in improving OER activity.