Schematic illustration of multilevel post-synthetic modification. a Effects of reduction reaction, Menshutkin reaction and multilevel post-synthetic modification on the bond change and charge state. b The synthesis of N+-COF, NH-COF and N+-NH-COF from the base COF (CoTAPP-PATA-COF). Credit: Nature Communications (2023). DOI: 10.1038/s41467-023-39544-9
Covalent organic frameworks (COFs), possessing ordered pores and high-precision functionalization, are regarded as an ideal class of templates to construct catalysts for electrocatalytic carbon dioxide reduction reaction (CO2RR).
C-N bonds can improve adsorption of CO2 and ionic skeletons can promote charge transfer, further enhancing conductivity. However, direct bottom-up synthesis can hardly realize co-existence of C-N bonds and ionic frameworks due to the electrostatic repulsion and weak strength of the linkage.
A research team led by Prof. Zeng Gaofeng and Assoc. Prof. Xu Qing from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences has proposed a multilevel post-synthetic modification strategy to construct catalytic COFs towards CO2RR with high activity and selectivity.
The results were published in Nature Communications.
Catalytic COFs synthesized by the post modification showed a maximum turnover frequency value of 9922.68 h–1 at –1.0 V and the highest faradaic efficiency of 97.32% at –0.8 V, which were higher than that of the base COF and the single-modified COFs.
Electrocatalysis tests and characterizations revealed that C-N bonds could improve catalytic selectivity and ionic skeleton contributed to higher activity.
Furthermore, theoretical calculations illustrated that the easier formation of immediate *CO from COOH* was the rate-determined step, and methyl groups strengthened electron density.
This work provides a deeper understanding of COFs in CO2 reduction reaction. It sheds light on constructing multilevel post-synthetic modification COFs towards tailored activity and high stability.
More information:
Minghao Liu et al, Post-synthetic modification of covalent organic frameworks for CO2 electroreduction, Nature Communications (2023). DOI: 10.1038/s41467-023-39544-9
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Researchers propose post-synthetic modification of covalent organic frameworks for carbon dioxide electroreduction (2023, July 6)
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