Unveiling the chemical reconstruction of Fe(OH)3-embedded Ni-MOF nanorods for enhanced oxygen evolution reaction

Abstract

Rationally designing metal–organic framework (MOF) electrocatalysts that can sustain industrial-level current densities in the oxygen evolution reaction (OER) remains a challenge, primarily due to limited understanding of their dynamic structure evolution—particularly the reconstruction of organic ligands. Here, we report Fe(OH)₃-embedded Ni-MOF (Fe/Ni-MOF) nanorods with abundant coordination defects that undergo electrochemical reconstruction to transform into CO₃²⁻-adsorbed Fe/NiOOH, achieving efficient and durable OER performance with overpotentials of 188, 231, and 250 mV at current densities of 10, 100, and 200 mA cm⁻², respectively, and maintaining stability over 180 hours in the industrial-level amperometry test. In situ Raman spectroscopy and post-reaction characterization studies co-reveal that CO₃²⁻, derived from the imidazole ligand, suppresses the dissolution of FeOOH at high current densities. Density functional theory (DFT) calculations further indicate that CO₃²⁻ adsorption lowers the energy barrier for the rate-determining step (OH* to O*) on Ni sites. These insights highlight the role of organic ligand reconstruction within MOFs, providing a robust strategy for designing durable and efficient nanoMOF electrocatalysts.