摘要：将二氧化碳（CO₂）还原为有价值的产物将有助于实现可持续的碳利用。本文报道了利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，通过光催化将CO₂还原为一氧化碳、甲酸盐和草酸盐离子的研究。在相似的照射条件下，与等摩尔量的单体吩嗪相比，P
本文要点：
将二氧化碳（CO₂）还原为有价值的产物将有助于实现可持续的碳利用。本文报道了利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，通过光催化将CO₂还原为一氧化碳、甲酸盐和草酸盐离子的研究。在相似的照射条件下，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，表明COF结构显著增强了催化性能（Phen-COF的转换频率：CO为10⁻⁷ s⁻¹，甲酸盐为10⁻⁸ s⁻¹，草酸盐为10⁻¹¹ s⁻¹）。通过X射线衍射和N₂孔隙度测定等结构分析，证实了COF的长程有序性和多孔性。机理研究表明，反应遵循甲酸盐到草酸盐的连续路径，CO和甲酸盐作为中间产物。这些结果展示了COF结构在提升无金属、氧化还原活性芳香体系（如吩嗪）性能方面的潜力，从而在温和条件下实现高效、选择性的CO₂转化。Figure 1. (a) Solvothermal synthesis of Phen-COF from the condensation of 1 and 2. (b) Schematic of the redox activity of Phen-COF and 1 involved in (c) the reduction of carbon dioxide to carbon monoxide, formate and oxalate.
Figure 2. (a) Powder x-ray diffraction (red) of Phen-COF powder. The simulated pattern of a theoretical AA-stacked structure is also shown (blue). (b) N2 isotherm of Phen-COF. (c) FTIR spectra of Phen-COF and 1. (d) Pore size distribution of Phen-COF.
Figure 3. (a) UV-Visible spectrum of Phen-COF and 1 (0.1 mM, acetonitrile containing 50 μM i-Pr2NEt). (b) Tauc plot of Phen-COF and 1 with the extrapolated optical bandgap. (c) Ultraviolet photoelectron spectrum for PhenCOFand 1 with zoom-in of the (d) valence band maxima determined for PhenCOFand 1.
Figure 4. (a) Schematic for gas line controllers and recirculating loop for in operando GCMS analysis. The flow rate into the custom glass photoreactor was maintained at 18.5 psi. (b) Representative CO production traces over time for Phen-COF and 1. (c) Optical image of the photoreactor containing Phen-COF under irradiation at 390 nm.
Figure 5. Ion chromatography traces of (a) formate produced after 13 hours by Phen-COF and 1 and (b) oxalate produced after 13 hours by Phen-COF and 1, including traces of reactions from Phen-COF and 1 after 13 hours without irradiation. (c) Determined amounts at varied time intervals by ex situ ion chromatography to quantify the amounts of formate and oxalate produced by COF and 1 throughout 13 hours of irradiation (14.5 mM Phen-COF or 1 in H2O/CH3CN/ i-Pr2NEt {7/1/2, 2 mL}, λ = 390 nm, SI Section X-XI). (d) Expansion of the plot in panel (c) to show the time-dependent formation of formate and oxylate by 1. Error bars in panels (c) and (d) depict the standard deviation of three measurements.
Figure 6. (a) Formate and oxalate produced from the photocatalytic reduction of carbon monoxide using Phen-COF. (b) Oxalate produced from the photocatalytic reduction of formate under a nitrogenatmosphere using Phen-COF. (40 mM of Phen-COF H2O/CH3CN/i-Pr2NEt. {7/1/2}, λ = 390 nm, 18.5 psi, 10 m. Error bars depict the standard deviation of three measurements.
来源：华算科技
