A collaborative team from the Dalian Institute of Chemical Physics (DICP) and Kunming University of Science and Technology has unveiled a powerful strategy to dramatically enhance photocatalytic hydrogen production by manipulating the "linkage isomerism" within covalent organic frameworks (COFs).
Published in the Chinese Journal of Catalysis (DOI: 10.1016/S1872-2067(26)65053-X) , the study demonstrates that subtle changes in how molecular building blocks are connected can trigger a nearly 100-fold increase in catalytic performance, offering a new blueprint for designing next-generation solar fuels materials.
Using a precise one-pot Povarov cyclization technique, the researchers synthesized two isomeric COFs—COF-PQ and COF-DPPQ—using identical starting materials but resulting in distinct atomic arrangements. While both frameworks are highly crystalline, their differences in connectivity led to vastly different electronic behaviors.
The star performer, COF-DPPQ, achieved a hydrogen evolution rate of 37.82 mmol g -1 h -1 and an apparent quantum efficiency of 8.9% at 500 nm, placing it among the most efficient COF-based photocatalysts reported to date.
To uncover why COF-DPPQ outperformed its counterpart so dramatically, the team combined ultrafast spectroscopy with theoretical simulations. They found that the unique linkage topology of COF-DPPQ optimizes the internal electric field, resulting in a much lower electron effective mass (0.574 vs. 1.046) and stronger donor-acceptor polarization (~0.95|e| vs. ~0.24|e|).
Furthermore, femtosecond transient absorption spectroscopy revealed that COF-DPPQ extends the average carrier lifetime to 37.28 picoseconds—nearly 30 times longer than COF-PQ. This suppression of electron-hole recombination ensures that more photogenerated electrons are available to drive the hydrogen evolution reaction.
The study also highlighted the critical role of the pore microenvironment. Molecular dynamics simulations showed that COF-DPPQ possesses a negatively charged surface that attracts protons, boosting proton adsorption capacity by 2.2-fold and increasing diffusion rates compared to COF-PQ.
"This work moves beyond simply tweaking surface chemistry," the authors note. "By treating linkage topology as a precision tuning knob, we can simultaneously engineer charge dynamics and mass transport pathways. This provides a generalizable paradigm for developing high-efficiency COF photocatalysts."
The research was supported by the National Natural Science Foundation of China, the State Key Laboratory of Catalysis, and the Liaoning Revitalizing Talents Program.
About the Journal
Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 17.2. The Editors-in-Chief are Profs. Can Li and Tao Zhang.
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Chinese Journal of Catalysis
Engineering channel microenvironment and charge dynamics in covalent organic frameworks through linkage-specific povarov cyclization for enhanced photocatalytic hydrogen evolution
2-Jul-2026