Bidentate-Ligand Molecular Bridge in NiFe-LDH as a Dynamic Proton Relay and Electronic Modulator to Enhance the Oxygen Evolution Reaction

The development of efficient and stable oxygen evolution reaction (OER) electrocatalysts is crucial for sustainable hydrogen production through water splitting. Though NiFe-layered double hydroxide (NiFe-LDH) represents a promising non-precious catalyst, its practical application is hindered by rapid degradation under operation due to metal leaching and sluggish kinetics. Bridged-linked structures were synthesized using a hydrothermal method. Inspired by the amino acids in photosystem II (PSII), we reported an organic–inorganic hybrid electrocatalyst of NiFe-LDH coupled with 4-chlorobenzoic acid (CA) that synchronously enhances OER activity and stability. The bidentate CA ligand bridges adjacent LDH layers via Fe-O-C and Fe-Cl-C bonds, modulating the electronic structure of metal centers and facilitating proton-coupled electron transfer. The resulting NiFe-LDH-CA exhibits an ultralow overpotential of 213 mV at 10 mA cm −2 , and remarkable stability over 550 h at 500 mA cm −2 in alkaline medium. It can also operate stably for 120 h under industrial conditions, experiencing virtually no performance degradation. In situ Raman spectroscopy and pH-dependent studies reveal that the anchored CA acts as a dynamic proton-transfer relay, facilitating concerted proton-electron transfer during OER. DFT calculations further confirm the reduced energy barrier of the rate-determining steps and promote the reaction kinetics. Additionally, the introduction of Fe-O-C/Fe-Cl-C bridge structure prevents the Fe species from dissolution during OER, thereby enhancing the stability of the catalyst. This work offers valuable insights for designing high-performance catalysts with bio-inspired proton-management functionality.