Restructuring hydrogen-bonding networks via hydroxyl-functionalized covalent organic frameworks for efficient nitrate electroreduction.

Hydroxyl-functionalized Cu-COF-4OH achieves a 93.20% ammonia Faradaic efficiency in nitrate electroreduction, outperforming most state-of-the-art catalysts.

• Why it matters: Efficient nitrate reduction is limited by slow proton transfer and low selectivity, hindering practical applications in nitrate removal and ammonia synthesis.
• What they did: A series of hydroxyl-functionalized copper phthalocyanine-based covalent organic frameworks (Cu-COF-nOH) were designed to regulate interfacial proton transfer through hydrogen-bonding network restructuring, with optimized hydroxyl loading promoting continuous hydrogen-bond chains.
• The result: The catalyst exhibits a high NH3 yield rate of 65.84 mg·h−1, excellent long-term stability, and reveals that hydroxyl-mediated hydrogen-bonding restructuring significantly enhances proton transfer kinetics and reaction selectivity.