Methyl-Induced Hydrophobicity and Electronically Tuned Copper Nanocluster COF for Highly Selective Nitrate to Ammonia Electrosynthesis
Year: 2026
Type: preprint
Abstract: Electrochemical nitrate reduction reaction (eNO3-RR) offers a promising route for sustainable ammonia production while mitigating nitrate pollution. Yet high NH3 selectivity remains challenging owing to proton-coupled multi-electron transfer pathways and competing hydrogen evolution reaction (HER). Herein, we report a trinuclear Cu nanocluster-based covalent organic framework (CuMePh) featuring methylfunctionalized π-conjugated extended porous framework that provides a molecular-level strategy for modifying the interfacial wettability and electronic environment of the catalytic framework. Benefiting from this modulation strategy, CuMePh exhibits a maximum faradaic efficiency (FE) of 98% for nitrate to ammonia conversion, with an NH3 production rate of 2161 μg h-1 cm-2 (5402.5 μg h-1 mg-1 cat.) at -0.5 V versus RHE under the investigated alkaline conditions. Compared with the non-methylated CuPh analogue, CuMePh also exhibits a higher water contact angle. Density functional theory (DFT) calculations reveal that the electronenriched Cu3-cluster nodes in CuMePh facilitate nitrate activation and sequential hydrogenation by lowering the free-energy requirement and optimizing intermediates binding, while simultaneously suppressing the competing HER. This work highlights a molecular-level design principle that couples electronic-structure engineering with interfacial-property regulation in nanocluster-based COFs, offering new opportunities for developing highly selective electrocatalysts for sustainable nitrogen-cycle transformations.
Source: ChemRxiv
Language: English
Subfield: Catalysis
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
Funders: Environmental Restoration and Conservation Agency, Kato Foundation for Promotion of Science, ENEOS Hydrogen Trust Fund, Iwatani Naoji Foundation, Amano Institute of Technology, Fujikura Foundation, Hosokawa Powder Technology Foundation, Japan Society for the Promotion of Science, National Institutes of Natural Sciences
Awards: Synthesis and crystallization of light-controlled metal nanocluster assemblies and elucidation of its physical properties, Construction of Functional Chemistry SystemUsing Precision Metal Nanoclusters as a Compositional Unit, G4255723654, G725513421, G8445925457, G9001302487, G9001302854, G9001303034
OpenAlex ID: W7223184572