Three-Dimensional Bicarbazole-Based Covalent Organic Frameworks as Efficient Yeager-Type Photocatalysts for H 2 O 2 Generation in a Two-Phase System

作者：Aiguo Kong, Tao Yang, Hai Yan, Xinxin Chen, Yue Chen, Fangyuan Kang, Qichun Zhang, Rui Liu · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.5c04447 · 被引用次数：104 · 研究领域：Covalent Organic Framework Applications、Advanced Photocatalysis Techniques、Metal-Organic Frameworks: Synthesis and Applications

Photocatalytic reduction of oxygen to hydrogen peroxide (H 2 O 2 ) represents an attractive solar-to-chemical conversion pathway. Nevertheless, it remains a significant challenge to achieve efficient H 2 O 2 photosynthesis while simultaneously mitigating photocorrosion of the catalysts owing to the presence of superoxide radicals ( • O 2 – ) and the accumulation of photoexcited holes (h + ). In the present work, a 1,2,3,4-tetrahydroisoquinoline (THIQ)-water two-phase system was developed to achieve high-efficiency and durable production of H 2 O 2 by suppressing • O 2 – intermediates and rapidly consuming h + . The • O 2 – -free direct two-electron oxygen reduction reaction (2e – ORR) to H 2 O 2 was accomplished on special three-dimensional (3D) covalent organic framework (COF) metal-free photocatalysts consisting of bicarbazole units (BCTB) as electron donors and thiazole (BT) or triazine (TAPT) as electron acceptors (COF-BCTB-BT or COF-BCTB-TAPT). The unique structures endow them with a high H 2 O 2 production rate in the water phase of ∼33.2 mmol g cat. –1 h –1 over COF-BCTB-BT. In the other organic phase, the photoexcited h + was also efficiently consumed by semidehydrogenation of THIQ (THIQ-SDR) to 3,4-dihydroisoquinoline (DHIQ). Theoretical calculations revealed a Yeager-type four-step direct 2e – ORR mechanism over two COFs, with a lower energy barrier of *O–O to *O–OH for COF-BCTB-BT. A four-step mechanism of the THIQ-SDR to DHIQ was also suggested. This work provides...