Amide-functionalized covalent triazine framework for enhanced photocatalytic hydrogen evolution

The crystallinity and building blocks or functional groups of covalent organic frameworks (COFs) are key points to tuning their photocatalytic performance. However, the functional groups and crystallinity remain difficult to coordinate. Herein, we report an amide-functionalized highly crystalline covalent triazine framework (CTF-amide-X), where the CF3SO3H-catalyzed trimerization strategy was applied to synthesize CTF-1, leading to a highly crystalline structure and numerous surface cyano groups. Through a simple HCl treatment, CTF-1 is amide-functionalized while maintaining high crystallinity, which substantially enhances photocatalytic activity in water splitting. Particularly, CTF-amide-16 exhibits a hydrogen-evolving rate of 1133 µmol g−1 h−1, far higher than that of pristine CTF-1. The superior activity of CTF-amide in photocatalysis can be obtained by promoting amide groups to separate photocarriers and promoting long-lived photoelectrons to aggregate on the material surface while maintaining the crystalline structure.