The strong coordination effect on FeNi-MOF derived catalyst for durable oxygen evolution reaction over 3000 h at operando condition

The in-situ evolved FeNi oxyhydroxide (FeNiOOH) derived from FeNi-based catalyst demonstrates exceptional intrinsic activity toward the oxygen evolution reaction (OER). However, its long-term stability is severely compromised by the dissolution of Fe sites. Herein, we introduce a strategy to enhance catalyst durability by leveraging the ligand effect of 4,4’-biphenyldicarboxylic acid (BPDC) derived from FeNi-based metal-organic framework (FeNi-MOF). As a result, the FeNi-MOF derived catalyst with ligand effect exhibits enhanced durability in alkaline OER, outperforming FeNi-layered double hydroxides (FeNi-LDH) by 6.2 times. Notably, the integrated FeNi-MOF/NF||Pt/C@NF electrolyzer sustains over 3000 h of operation at 500 mA·cm⁻² with minimal degradation (0.0737 mV·h⁻¹). In-situ Raman spectroscopy confirms that, compared to FeNi-LDH, the ligand effect of BPDC accelerates the evolution of FeNi-MOF into BPDC-functionalized FeNiOOH (FeNiOOH-BPDC) and enhances the degree of reconstruction, thereby promoting the activity of OER. X-ray photoelectron spectroscopy analysis and density functional theory calculations demonstrate that in-situ anchored BPDC enriches the electron density around Fe atoms, reducing the Fe oxidation state and strengthening the Fe–O bonds, thereby preventing the excessive oxidation of Fe and inhibiting Fe dissolution. This work highlights the critical role of BPDC ligand in stabilizing FeNi-based OER catalysts and offers a promising strategy for designing industrially stable catalysts.