Article Highlight | 22-Jul-2026

Modulating in-plane conjugation and core polarity in naphthalimide-based covalent organic frameworks enables efficient H2O2 photosynthesis

Shanghai Jiao Tong University Journal Center

Electronic Structure Engineering of Naphthalimide-Based COFs for Efficient H2O2 Photosynthesis

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  • Naphthalimide-based donor–acceptor COFs were constructed by integrating an NDI acceptor unit with different aromatic donor cores to regulate electronic properties.
  • Increasing in-plane conjugation and decreasing core polarity promote charge separation and directional carrier transport, enhancing photocatalytic activity.
  • Under visible-light irradiation, the optimized COF drives coupled oxygen reduction reaction (ORR) and water oxidation reaction (WOR) pathways to achieve efficient H2O2 photosynthesis from O2 and H2O.
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Credit: Qiang Ma, Guang-en Fu, Junyi Han, Yuan Chen, Mengwei Chen, Haoyong Yang, Juanfang Xu, Jianing Wang, Paolo Samori and Tao Zhang.

A study published in Transformative Chemistry by Qiang Ma, Guang-en Fu, Junyi Han, Yuan Chen, Mengwei Chen, Haoyong Yang, Juanfang Xu, Jianing Wang, Paolo Samori and Tao Zhang from Chinese Academy of Sciences reports a series of naphthalimide(NDI)-based donor–acceptor covalent organic frameworks (COFs) with tunable in-plane conjugation and core polarity for photocatalytic H2O2 production. By regulating the electronic structure of the COFs, the authors identified NDI–B–COF(benzene core) as the most efficient photocatalyst, achieving H2O2 photosynthesis from water and oxygen under visible light with a production rate of up to 11,025 μmol g-1 h-1 and excellent stability.

Why This Research Matters
· Improving metal-free H2O2 photosynthesis: Sustainable H2O2 production requires efficient photocatalysts with effective charge separation and transport. The optimized NDI–B–COF exhibited enhanced photocurrent response and lower charge-transfer resistance, leading to improved H2O2 generation performance. This system outperforms other COFs comprising nitrogen (NDI–N–COF) and triazine (NDI–T–COF) cores.

· Providing a design strategy for COF photocatalysts: The study shows how simultaneous regulation of in-plane conjugation and core polarity influences charge transport and catalytic activity. These structure–property relationships offer guidance for developing more efficient COF-based materials for solar energy conversion.

Innovative Design and Mechanisms

·Electronic structure engineering: Three NDI-based donor–acceptor COFs with different core structures were constructed to modulate conjugation and polarity. The benzene-core NDI–B–COF provided superior carrier separation and transport properties.

·Dual reaction pathways revealed: EPR, in situ DRIFTS, and DFT calculations showed that H2O2 formation proceeds through coupled two-electron oxygen reduction (ORR) and indirect two-electron water oxidation (WOR) pathways. Electron transfer occurs from the amine units to the imine and NDI carbonyl sites, while the NDI carbonyl groups serve as key reaction centers.

Applications and Future Outlook
The study demonstrates that synergistic regulation of in-plane conjugation and core polarity can effectively tune the electronic properties of COFs and enhance photocatalytic performance. This strategy provides a framework for developing next-generation metal-free photocatalysts for solar-driven H2O2 production and related energy conversion processes.

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