Hirani Zoheb, Schweitzer Neil M, Vitaku Edon, Dichtel William R
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
Angew Chem Int Ed Engl. 2025 May;64(21):e202502799. doi: 10.1002/anie.202502799. Epub 2025 Mar 18.
The reduction of carbon dioxide (CO₂) into valuable products will contribute to sustainable carbon use. Here we report the photocatalytic reduction of CO₂ to carbon monoxide, formate, and oxalate ions using a redox-active phenazine-based 2D covalent organic framework (Phen-COF) and its phenazine monomer. Under similar irradiation conditions, Phen-COF produced 2.9 times more CO, 11 times more formate, and 13 times more oxalate compared to equimolar amounts of the monomeric phenazine, demonstrating that the COF architecture enhances catalytic performance (TOF: 10 s CO, 10 s formate, and 10 s oxalate). Structural analysis, including X-ray diffraction and N₂ porosimetry, confirmed the COF's long-range order and porosity. Mechanistic studies suggest a sequential formate-to-oxalate pathway, with CO and formate acting as intermediates. These results demonstrate the potential of the COF architecture to improve the performance of metal-free, redox-active aromatic systems such as phenazines to facilitate efficient and selective CO₂ conversion under mild conditions.
将二氧化碳（CO₂）还原为有价值的产物将有助于实现碳的可持续利用。在此，我们报告了使用基于氧化还原活性吩嗪的二维共价有机框架（Phen-COF）及其吩嗪单体将CO₂光催化还原为一氧化碳、甲酸盐和草酸盐离子的过程。在相似的辐照条件下，与等摩尔量的单体吩嗪相比，Phen-COF产生的CO多2.9倍、甲酸盐多11倍、草酸盐多13倍，这表明COF结构增强了催化性能（TOF：CO为10 s⁻¹、甲酸盐为10 s⁻¹、草酸盐为10 s⁻¹）。包括X射线衍射和N₂孔隙率测定在内的结构分析证实了COF的长程有序性和孔隙率。机理研究表明存在一条从甲酸盐到草酸盐的连续途径，其中CO和甲酸盐作为中间体。这些结果证明了COF结构在改善无金属、氧化还原活性芳香体系（如吩嗪）的性能方面的潜力，以便在温和条件下促进高效且选择性的CO₂转化。
