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-LDH by 6.2 times. Notably, the integrated FeNi-MOF/NF||Pt/C@NF electrolyzer sustains over 3000 hours 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 strengthen 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.