Ferrocene-Based Metal Hydroxide-Organic Frameworks: Synergistic Electronic Modulation for Efficient Oxygen Evolution...

The development of efficient oxygen evolution reaction (OER) electrocatalysts is critical for advancing water electrolysis as a sustainable hydrogen production technology. As OER electrocatalysts, conventional layered double hydroxides (LDHs) and metal-organic frameworks (MOFs) suffer from inherent limitations, including poor active sites accessibility and structural instability. Our work introduces a novel ferrocene-incorporated metal hydroxide-organic framework (FcMHOF) prepared using hydrothermal template-directed synthesis. This hybrid architecture uniquely merges the excellent electrocatalytic properties characteristic of nickel-iron layered double hydroxides (NiFe-LDHs) with the structural adaptability of MOFs. The as-prepared FcMHOF catalyst displays several advantageous features: homogeneous active site distribution, well-defined hierarchical porosity, and flexible metal-ligand coordination environments. These attributes collectively address diffusion limitations while promoting favorable adsorption energetics for key reaction intermediates. Electrocatalytic experiments in alkaline media (1 M KOH) reveal remarkable catalytic performance, including a minimal overpotential of 276 mV at 10 mA cm^-2, an exceptionally low Tafel slope (38 mV dec^-1), and outstanding stability, surpassing both commercial IrO₂ and leading reference materials. Ex situ and in situ spectroscopic analyses reveal that FcMHOF undergoes dynamic structural reconstruction during OER operation, with partial transformation into γ-NiFeOOH phases. In the catalytic phase, the in situ formed γ-NiFeOOH with rich NiFe interactions and elongated metal-oxygen (M-O) bonds serves as active sites to enhance OER performance, while the lattice oxygen-mediated mechanism (LOM) adopted by these catalytic sites balances the lattice oxygen regeneration and ensures durability improvement. The synthetic methodology and mechanistic insights presented herein provide valuable insights for designing more efficient OER catalysts.