Unlocking d–p Orbital Coupling via Built‐in Electric Fields for High‐Performance Hydrazine Hydrate Fuel Cell

ABSTRACT Direct hydrazine fuel cells (DHzFCs) offer a promising carbon‐free liquid‐fuel route for power generation, yet progress is limited by sluggish hydrazine oxidation reaction (HzOR) kinetics and the high cost of Pt catalysts. In this work, we tune the built‐in electric field (BIEF) at the Pt@MOF interface via linker‐directed defect engineering. Partial substitution of 1,1′‐ferrocenedicarboxylic acid (Fc) with ferrocene–carboxylic acid (Fc') generates graded ligand‐defect and undercoordinated Ni─O environments, thereby regulating Pt anchoring and interfacial charge redistribution. The optimized Pt@NiFc 0.95 Fc' 0.05 ‐MOF delivers 1000 mA cm–2 for HER (180 mV, overpotential) and 2000 mA cm–2 for HzOR (346 mV, working potential), outperforming Pt/C while achieving 99% hydrazine conversion. The assembled direct hydrazine hydrate–hydrogen peroxide fuel cell (DHHPFC) delivers a peak power density of 441 mW cm −2 at 80°C. Density functional theory (DFT) calculations and experimental analyses reveal that the oxygen‐mediated Pt─O─Ni interfacial electronic pathway, enhanced apparent BIEF, and accelerated interfacial charge transfer in Pt@NiFc 0.95 Fc' 0.05 ‐MOF, accounts for the improved catalytic and fuel‐cell performance. This work establishes a linker‐defect strategy for constructing Pt‐utilization‐efficient interfaces for hydrazine energy conversion.