Methyl-Induced Hydrophobicity and Electronically Tuned Copper Nanocluster COF for Highly Selective Nitrate to Ammonia Electrosynthesis
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.
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BibTeX
@misc{bhandari2026methylinduced,
title = {{Methyl-Induced Hydrophobicity and Electronically Tuned Copper Nanocluster COF for Highly Selective Nitrate to Ammonia Electrosynthesis}},
author = {Sriyanka Bhandari and Somnath Paitandi and Rohit Sankapal and Jumana Ishrat and Imran Hussain and Sabuj Kanti Das and Sujan Mondal and Riki Nakatani and Tokuhisa Kawawaki and Kalishankar Bhattacharyya and Cafer T. Yavuz and Yuichi Negishi},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010880/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010880/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Methyl-Induced Hydrophobicity and Electronically Tuned Copper Nanocluster COF for Highly Selective Nitrate to Ammonia Electrosynthesis
AU - Sriyanka Bhandari
AU - Somnath Paitandi
AU - Rohit Sankapal
AU - Jumana Ishrat
AU - Imran Hussain
AU - Sabuj Kanti Das
AU - Sujan Mondal
AU - Riki Nakatani
AU - Tokuhisa Kawawaki
AU - Kalishankar Bhattacharyya
AU - Cafer T. Yavuz
AU - Yuichi Negishi
PY - 2026
DA - 2026/10/22
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010880/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010880/v1
AB - 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.
ER -