Zou Lei, Si Duanhui, Yang Shuailong, Chen Ziao, Huang Yuanbiao, Cao Rong
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P. R. China.
Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian, 350108, P. R., China.
Angew Chem Int Ed Engl. 2025 Feb 3;64(6):e202418319. doi: 10.1002/anie.202418319. Epub 2024 Dec 17.
Imine-based covalent organic frameworks (COFs) are promising for photocatalytic water splitting, but their performance is often constrained by inefficient charge separation due to the high electron localization nature of polar imine bonds. In this study, we have optimized the electron delocalization across the imine linkage within a COF by implementing a charge compensation effect. This effect is achieved when a strong electron-donating thieno[3,2-b]thiophene linker is directly attached to the iminic carbon of a zinc-porphyrinic COF. This modification significantly reduces the electron binding effect within the imine bonds of the COF, facilitating both in-plane charge separation and out-plane charge transfer to the catalytic site. Conversely, the use of strong electron-withdrawing pyrizine linker aggravates the electron localization at the imine linkage in the ZnP-Pz variant. Consequently, ZnP-Tt shows a substantially improved photocatalytic water-splitting activity under visible light irradiation, with a hydrogen evolution of 44288±2280 μmol g in 4 h, which exceeds the ZnP-Pz counterpart by a factor of 10. These results offer fresh perspectives for the design of imine-based COFs to overcome their limitations in charge separation efficiency.
基于亚胺的共价有机框架（COFs）在光催化水分解方面具有潜力，但其性能常常受到限制，因为极性亚胺键的高电子定域性导致电荷分离效率低下。在本研究中，我们通过实现电荷补偿效应优化了COF中亚胺键上的电子离域。当一个强供电子的噻吩并[3,2 - b]噻吩连接体直接连接到锌卟啉COF的亚胺碳上时，就实现了这种效应。这种修饰显著降低了COF亚胺键内的电子束缚效应，促进了面内电荷分离和面外电荷向催化位点的转移。相反，使用强吸电子的吡嗪连接体加剧了ZnP - Pz变体中亚胺键处的电子定域。因此，ZnP - Tt在可见光照射下表现出显著提高的光催化水分解活性，4小时内析氢量为44288±2280 μmol g，比ZnP - Pz对应物高出10倍。这些结果为设计基于亚胺的COFs以克服其电荷分离效率方面的局限性提供了新的视角。
