Covalent organic frameworks (COFs) have emerged as versatile platforms for photocatalysis. In recent years, increasing attention has been directed toward extending the light-harvesting capability of COF-based photocatalysts into the narrow bandgap region to utilize a broader portion of the solar spectrum. Herein, we report a post-synthetic thermal azide–alkyne cycloaddition (TAAC) strategy to covalently integrate porphyrin chromophores onto COF pore walls, thereby enhancing visible-light absorption and modulating photogenerated charge harvesting efficiency. Our results demonstrate that alkyne-functionalized porphyrins can be efficiently and robustly coupled to azide-containing COFs through a simple metal-free thermal reaction, achieving molecular-level dispersion without aggregation. The incorporation of porphyrins significantly extends light harvesting into the 500–700 nm region and leads to an approximately threefold enhancement in H2O2 production under 660 nm irradiation in the presence of a sacrificial agent. In contrast, control experiments with non-immobilized molecular porphyrin exhibits negligible photocatalytic activity under identical conditions, highlighting the importance of spatial confinement and controlled dispersion for effective exciton utilization. Furthermore, metallation of the integrated porphyrins provides an additional strategy to regulate photogenerated electron harvesting yields, enabling further tuning of photocatalytic performance. This work establishes post-synthetic chromophore integration as a powerful approach to engineer light harvesting and charge separation in COF-based photocatalysts for solar-driven H2O2 production.
Wang et al. (Mon,) studied this question.