Constructing Catalytic Crown Ether-Based Covalent Organic Frameworks for Electroreduction of CO₂

Electrochemical reduction of carbon dioxide is significant for carbon-neutral clean energy. Catalytic covalent organic frameworks (COFs) constructed with metalloporphyrin skeletons are an ideal alternative for transformation of carbon dioxide to carbon monoxide. However, the strong hydrophobicity and the poor electron-transfer ability of the COFs limit their catalytic performance. Herein, a crown ether and cobalt-porphyrin-based COF (TAPP(Co)-B18C6-COF) has been developed to catalyze carbon dioxide reduction. The crown ether units integrated in the COFs not only enhance the hydrophilicity of the frameworks but also promote the electron transfer from crown ether to the Co-porphyrin cores. In addition, the crown ether units enhance the binding ability of carbon dioxide. By virtue of these features, the catalytic COF showed remarkable catalytic performance with Faradaic efficiencies (FECO) of 84.4–93.2% at applied potentials between −0.60 and −0.90 V vs RHE, with the maximum TOF of 1267 h–1 at −0.9 V. This work provides new insights into COFs and electrocatalysis.