A novel phenolic pyrylium-based porous organic polymer promotes solar-driven photocatalytic CO2 reduction

Research on ionic porous organic polymers (iPOPs) for photocatalytic carbon dioxide (CO 2 ) reduction has shown promising progress over the past decade, but improving their catalytic performance in CO 2 reduction remains a challenge. In this work, neutral monomer 2,6-dimethyl-γ-pyrone (DMPy) is employed into iPOPs (Py-POPOH) via Aldol condensation, where acidic conditions could not only catalyze the reaction, but also convert DMPy from quinoid structure to phenol-based pyrylium. The cationic sites facilitate the electrostatic adsorption of CO 2 , while the phenol structures aid in electron delocalization across the pyrylium, thereby broadening the photoresponse range and increasing the charge separation efficiency. Moreover, the phenolic hydroxyl intensifies the interaction with CO 2 through hydrogen bonds, leading to improved photocatalytic performance. The resultant Py-POPOH exhibits significant advancement in light absorption, extending to 792 nm, and achieves a high CO 2 to CO conversion rate of 237.75 µmol g -1 h −1 as metal-free photocatalysts, almost 6 times higher than that of phenol-free structure. This result demonstrates the potential of iPOPs in improving photocatalytic performance, and provides a way to further improve the design of photocatalysts.