Resorcinol–Azodianiline\nCovalent Organic Framework\nSupported FeOOH Quantum Dot-Catalyzed Electrochemical Ammonia Synthesis\nunder Ambient Conditions

Covalent organic frameworks (COFs) represent bulk crystalline\norganic\npolymers characterized by their significant surface area and well-organized\npores. By carefully selecting building blocks, we can tailor COF structures\nwith strategically placed heteroatoms. This deliberate inclusion enhances\ntheir stability, surface area, and guest-binding ability, which make\nthem highly versatile catalyst supports. Importantly, heteroatoms\nwithin COF pores under an applied potential can amplify the catalyst’s\ndesired properties. FeOOH, when grown as nanosized QDs, can exhibit\nsemiconducting band gaps, and their amorphous form can be rich in\ndefects, making them catalytically active. Here, we synthesized a\nheterogeneous electrocatalyst (FeOOH@COF) consisting of FeOOH supported\non an imine-linked covalent organic framework (IISERP-COF33) under\nmild conditions. Electron microscopy, ICP, and XPS validate the homogeneous\ndistribution (13.2 wt %) of nanosized FeOOH quantum dots (QDs) within\nthe COF (average particle size distribution: 2.7 nm). Thus, the Lewis–Bronsted\nacidity-rich FeOOH accommodated at keto and nitrogen-rich anchoring\nsites within the COF pores defines the active and recyclable electrocatalyst.\nThis composite system catalyzes ambient condition ammonia production\nfrom nitrogen with a yield of 77.4 μg h<sup>–1</sup> mg<sub>cat</sub><sup>–1</sup> and faradaic efficiency of 46.4% at\n−0.4 V in 0.1 M LiClO<sub>4</sub> aqueous solution, surpassing\nother COF and iron-based electrocatalysts reported thus far. This\nwork elucidates an accessible aqueous-stable COF-QD electrocatalyst\nfor energy-efficient ammonia production.