Integrating Enrichment, Reduction, and Oxidation Sites in One System for Artificial Photosynthetic Diluted CO₂ Reduction.

Abstract

Artificial photosynthetic diluted CO₂ 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 CO₂ enrichment, CO₂ reduction and H₂ O oxidation sites is designed for diluted CO₂ 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]BF₄ @Zn-S-COF shows a visible-light-driven CO₂ -to-CO conversion rate of 105.88 µmol g^-1 h^-1 under diluted CO₂ (15%) atmosphere, even superior than most photocatalysts in high concentrations CO₂ . Moreover, natural sunlight driven diluted CO₂ 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 H₂ O oxidation and CO₂ reduction sites, and the loaded ILs provide an enriched CO₂ atmosphere, realizing the efficient photocatalytic activity in diluted CO₂ reduction.