Molecular Weaving of Mixed‐Addenda Polyoxometalates into MOF Nanochannels as Electron‐Buffering Reservoirs for Enhanced Nitrate‐to‐Ammonia Electrocatalysis

ABSTRACT Electrochemical conversion of nitrate pollutants into value‐added ammonia (e‐NO 3 RA) offers a sustainable pathway for nitrogen valorization, yet hinges on the development of efficient electrocatalysts. Herein, we systematically synthesize a series of three V/W mixed‐addenda polyoxometalate ([P 2 W VI 17 V V 1 O 62 ] 7− , noted as P 2 W 17 V 1 ) based metal–organic frameworks [X 9 (DPYB) 9 (OX) 6 (H 2 O) 6 ][P 2 W 17 V 1 O 62 ] denoted as XMOF‐V 1 (X = Fe; Co; Zn, DPYB = 1,4‐Di(pyridin‐4‐yl)benzene, OX = oxalic acid). The incorporation of P 2 W 17 V 1 not only reinforced structural ruggedness and stability, but also promotes multi‐electron transfer, substantially promoting e‐NO 3 RA activity. Among them FeMOF‐V 1 delivers exceptional electrocatlytic nitrat‐to‐ammonia performance with an achieves over 95% Faradaic efficiency across a wide voltage range of −0.6 to −1.4 V vs RHE. This superiority stems from synergistic interplay: P 2 W 17 V 1 acts as an electron reservoir enhancing proton‐coupled charge transfer, while the minimal bandgap of FeMOF‐V 1 facilitates directional electron injection. DFT analyses reveal Fe‐specific mechanisms including strong 3 d ‐orbital hybridization with NO 3 – near Fermi Level (Ef), highly positive Fe sites optimizing adsorption, and transfer weakening N–O bonds, as corroborated by in situ FTIR identification of *NO 3 /*NO/*NH 2 intermediates. Together with effectively suppressed HER (ΔG *H > ΔG *NO3 ), these attributes collectively enable highly selective NH 3 synthesis. This study establishes mixed‐addenda POMOFs as a versatile and efficient platform for sustainable nitrate‐to‐ammonia conversion.