本文要点：
金属配位共价有机框架(COFs)由于其预先设计的结构和定制的金属中心微环境，是理解二氧化碳(CO2)还原的构效关系的潜在平台。
在本文中，作者设计并合成了一种含三齿螯合配体(2,6-双(亚氨基)吡啶)的COF与过渡金属(命名为M-PDI-COF，M = Ni,Co,Fe,Zn,Mn)结合，用于促进CO2的光还原。
在可见光照射下，基于“Ni–N3Cl2”配位环境的Ni-PDI-COF的最佳催化体系产生4437 µmol g–1 h–1 的一氧化碳(CO ),对氢(H2)的选择性接近100 %( 0.08 MPa ),并且在相对高的CO2压力(0.15 MPa)下显示出10164 µmol g–1 h–1 的CO，对H2的选择性为98%。
原位/非原位实验和理论计算的结果表明，与PDI-COF相比,“Ni–N3Cl2”位点可以改善电荷转移动力学，抑制光生电子-空穴对的复合，减少速率控制步骤(*CO2转化为*COOH)的障碍，并改善反应动力学，从而提高CO2光还原反应的活性和选择性。
这项研究为研究配位构象对CO2光还原金属基COF催化剂的影响提供了重要的见解。
Fig. 1. Design and synthesis of M-PDI-COFs with tri-coordination moiety (M–N3) catalytic sites. (a) The typical coordination modes in COFs. (b) The schematic diagram for the construction of M–N3 moiety in M-PDI-COFs.
Fig. 2. Crystallinity and porosity analysis of PDI-COF and Ni-PDI-COF.
Fig. 3. The morphology and coordination environment analysis of Ni-PDI-COF.
Fig. 4. Optical characterization of PDI-COF and Ni-PDI-COF.
Fig. 5. The photocatalytic CO2 reduction performance of PDI-COF and Ni-PDI-COF. Photocatalytic CO production (a) and selectivity for CO over H2 (b) using Ni-PDI-COF under visible light irradiation. (c) CO production under diverse reaction conditions. (d) Mass spectrum of 13CO (m/z = 29) produced by Ni-PDI-COF in the photocatalytic reduction of 13CO2. (e) Cyclic stability tests of Ni-PDI-COF for CO2 photoreduction. (f) Comparison of CO production rate and CO selectivity of various COFs containing metals for CO2 photoreduction.
Fig. 6. Characterization and DFT calculation for the mechanism investigation. The 3D fs-TA spectra of PDI-COF (a) and Ni-PDI-COF (b) at probe wavelengths from 425 to 750 nm. (c) TA kinetic plots and typical fitting curves of PDI-COF and Ni-PDI-COF probed at a probe wavelength of 550 nm. (d) In situ Ni 2p2/3 XPS spectra for the simulated solar-driven CO2 reduction process over Ni-PDI-COF. (e) In situ DRIFTS spectra for the simulated solar-driven CO2 reduction process over Ni-PDI-COF. (f) Free energy diagrams for CO2 reduction to CO on Ni–N3Cl2 in Ni-PDI-COF.
https://doi.org/10.1016/j.apcatb.2025.125117
