Covalent organic frameworks (COFs) have recently emerged as a kind of promising photocatalytic platform in addressing the growing threat of trace pollutants in aquatic environments. Along this, we propose a strategy of constructing internal electric field (IEF) in COFs through the dipole moment regulation, which intrinsically facilitates the separation and transfer of photogenerated excitons. Two COFs of BTT-TZ-COF and BTT-TB-COF are developed by linking the electron-donor of benzotrithiophene (BTT) block and the electron-acceptor of triazine (TZ) or tribenzene (TB) block, respectively. DFT calculations demonstrate TZ block with larger dipole moment can achieve more efficient IEF due to the stronger electron-attractive force and hence narrower bandgap. Moreover, featuring the highly-order crystalline structure for accelerating photo-excitons transfer and rich porosity for facilitating the adsorption, BTT-TZ-COF exhibited an excellent universal performance of photocatalytic degradations of various dyes. Specifically, a superior photodegradation efficiency of 99% Rhodamine B (RhB) is achieved within 20 min under the simulated sunlight. Therefore, this convenient construction approach of enhanced IEF in COFs through rational regulation of the dipole moment can be a promising way to realize high photocatalytic activity.

中文翻译：

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增强共价有机框架光催化剂内电场的偶极矩调节

共价有机框架（COF）最近已成为一种有前景的光催化平台，可解决水生环境中痕量污染物日益增长的威胁。为此，我们提出了一种通过偶极矩调节在COF中构建内电场（IEF）的策略，这从本质上促进了光生激子的分离和转移。 BTT-TZ-COF和BTT-TB-COF这两种COF是通过分别连接苯并三噻吩(BTT)块的电子给体和三嗪(TZ)或三苯(TB)块的电子受体而形成的。 DFT 计算表明，具有较大偶极矩的 TZ 块可以实现更有效的 IEF，因为电子吸引力更强，因此带隙更窄。此外，BTT-TZ-COF具有加速光激子转移的高有序晶体结构和促进吸附的丰富孔隙率，在光催化降解各种染料方面表现出优异的通用性能。具体而言，在模拟阳光下 20 分钟内即可实现 99% 的罗丹明 B (RhB) 光降解效率。因此，这种通过合理调节偶极矩在COF中增强IEF的便捷构建方法可能是实现高光催化活性的一种有前途的方法。