Yang Tao, Kong Fantao, Chen Yue, Kong Aiguo, Cui Xiangzhi, Shi Jianlin
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P.R. China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Angew Chem Int Ed Engl. 2025 Apr 7;64(15):e202424110. doi: 10.1002/anie.202424110. Epub 2025 Feb 5.
Pairing photocatalytic 1,2,3,4-tetrahydroisoquinoline semi-dehydrogenation reaction (THIQ-SDR) with two-electron oxygen reduction reaction (2e ORR) is a green solar to chemical strategy by simultaneously utilizing the photo-excited electrons and holes. However, it is still short of high-efficiency photocatalyst to drive two reactions above. In the present work, crystalline pyrene-thiourea/urea covalent organic frameworks (COF-Py-S and -O) were synthesized and demonstrated as high-performance metal-free photocatalysts. In particular, COF-Py-S exhibited higher 2e ORR to HO yield rate of 19 mmol g h under visible light and finally solid HO products (NaCO ⋅ 1.5HO) was collected after long-time irradiation. Under natural sunlight conditions, the HO production rate over COF-Py-S further increased to ~51 mmol g h, among the best COF photocatalysts. COF-Py-S also showed high THIQ-SDR conversion (100 %) with 3,4-dihydroisoquinoline (DHIQ) selectivity of ~92 %. Theoretical calculations reveal stronger electron push-pull effect of COF-Py-S than COF-Py-O, enhancing its photoinduced charge carries, and a four-step 2e ORR mechanism with thiourea as the active sites has been confirmed as well as the mechanism of THIQ-SDR to DHIQ, featuring lower energy barriers for O adsorption and *HOOH desorption over thiourea units. This work provides a paired photosynthesis strategy of HO and DHIQ over high-efficiency pyrene-(thio)urea COF photocatalysts with electron push-pull effect.
将光催化1,2,3,4-四氢异喹啉半脱氢反应（THIQ-SDR）与双电子氧还原反应（2e ORR）相结合，是一种通过同时利用光激发电子和空穴的绿色太阳能到化学能的策略。然而，目前仍缺乏高效的光催化剂来驱动上述两个反应。在本工作中，合成了结晶芘-硫脲/脲共价有机框架（COF-Py-S和-O），并证明它们是高性能的无金属光催化剂。特别是，COF-Py-S在可见光下表现出较高的双电子氧还原反应生成过氧化氢的产率，约为19 mmol g⁻¹ h⁻¹，长时间照射后最终收集到固态过氧化氢产物（Na₂CO₃·1.5H₂O）。在自然阳光条件下，COF-Py-S的过氧化氢生成速率进一步提高到约51 mmol g⁻¹ h⁻¹，是最佳的COF光催化剂之一。COF-Py-S还表现出较高的THIQ-SDR转化率（约100%），对3,4-二氢异喹啉（DHIQ）的选择性约为92%。理论计算表明，COF-Py-S的电子推拉效应比COF-Py-O更强，增强了其光生电荷载流子，同时证实了以硫脲为活性位点的四步双电子氧还原反应机制以及THIQ-SDR生成DHIQ的机制，其特征在于硫脲单元上氧吸附和*HOOH脱附的能垒较低。这项工作提供了一种在具有电子推拉效应的高效芘-（硫）脲COF光催化剂上同时合成过氧化氢和DHIQ的配对光合作用策略。
