Hydrogen peroxide (H₂O₂) is an essential eco-friendly oxidant, but its conventional anthraquinone-based production is energy-intensive and generates hazardous waste. Photocatalysis offers a sustainable, solar-driven alternative. Organic polymer photocatalysts, notably covalent organic frameworks (COFs), have gained attention due to their tunable structures, earth-abundant elements, and visible-light responsiveness. Although recent advances (e.g., polarity-optimized, fluorinated, or sulfone-containing COFs) have improved H₂O₂ yields and extended stability to 336 hours, long-term durability remains limited. Most systems exhibit reaction times of less than 200 hours due to oxidative decomposition from accumulated photogenerated holes. This accumulation results from mismatched kinetics between rapid oxygen reduction reaction (ORR) and sluggish water oxidation reaction (WOR), where slow hole consumption causes bond cleavage (e.g., imine-to-amide transformation or alkyne degradation). Current strategies fail to adequately balance ORR/WOR kinetics, hindering practical applications.
A research team led by Prof. Bien Tan, Dr. Xiaoyan Wang, and Prof. Xuan Yang at Huazhong University of Science and Technology designed a COF-based photocatalyst incorporating reversible hydroquinone groups for H₂O₂ production. The resulting Tz-QH-COF balances WOR kinetics and prevents photocatalyst oxidation, achieving exceptional long-term photocatalytic stability. The results were published in the Chinese Journal of Catalysis ( DOI: 10.1016/S1872-2067(25)64676-6 ).
Tz-QH-COF was synthesized via a solvothermal Schiff-base condensation reaction. Incorporating the hydroquinone (QH) unit into the Tz-QH-COF structure enhanced oxidation potential, exciton dissociation, and water affinity, thereby improving photocatalytic performance. Under visible light, Tz-QH-COF achieves a high H₂O₂ production rate of 937 μmol h⁻¹ in pure water and sustains activity for 528 hours—far surpassing previous organic photocatalysts. Using an "atmosphere-switching" strategy (O₂/N₂ cycling), it accumulates 18.6 mM H₂O₂ after 120 hours, demonstrating remarkable durability.
In situ ATR-SEIRAS and DFT simulations reveal the redox-mediated stabilization mechanism: (1) In an O₂ atmosphere, photoexcited QH oxidizes to benzoquinone (Q), driving 2e⁻ ORR to produce H₂O₂; (2) Under N₂, Q regenerates to QH via WOR, preventing hole accumulation and oxidative degradation. This reversible QH/Q cycle dynamically reconciles disparate ORR/WOR kinetics, eliminating photocorrosion. This work establishes a molecular-level strategy for designing robust, long-lived photocatalysts for solar-driven H₂O₂ synthesis.
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 15.7. The Editors-in-Chief are Profs. Can Li and Tao Zhang.
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