Integrating Enrichment, Reduction, and Oxidation Sites in One System for Artificial Photosynthetic Diluted CO 2 Reduction

Abstract Artificial photosynthetic diluted CO 2 reduction directly driven by natural sunlight is a challenging, but promising way to realize carbon‐resources recycling utilization. Herein, a three‐in‐one photocatalytic system of CO 2 enrichment, CO 2 reduction and H 2 O oxidation sites is designed for diluted CO 2 reduction. A Zn‐Salen‐based covalent organic framework (Zn‐S‐COF) with oxidation and reductive sites is synthesized; then, ionic liquids (ILs) are loaded into the pores. As a result, [Emim]BF 4 @Zn‐S‐COF shows a visible‐light‐driven CO 2 ‐to‐CO conversion rate of 105.88 µmol g −1 h −1 under diluted CO 2 (15%) atmosphere, even superior than most photocatalysts in high concentrations CO 2 . Moreover, natural sunlight driven diluted CO 2 reduction rate also reaches 126.51 µmol g −1 in 5 h. Further experiments and theoretical calculations reveal that the triazine ring in the Zn‐S‐COF promotes the activity of H 2 O oxidation and CO 2 reduction sites, and the loaded ILs provide an enriched CO 2 atmosphere, realizing the efficient photocatalytic activity in diluted CO 2 reduction.