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 on June 26.
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.
