Controlling the Polarity of Metal–Organic Frameworks to Promote Electrochemical CO 2 Reduction

The addition of polar functional groups to porous structures is an effective strategy for increasing the ability of metal-organic frameworks (MOFs) to capture CO₂ by enhancing interactions between the dipoles of the polar functional groups and the quadrupoles of CO₂. However, the potential of MOFs with polar functional groups to activate CO₂ has not been investigated in the context of CO₂ electrolysis. In this study, we report a mixed-ligand strategy to incorporate various functional groups in the MOFs. We found that substituents with strong polarity led to increased catalytic performance of electrochemical CO₂ reduction for these polarized MOFs. Both experimental and theoretical evidence indicates that the presence of polar functional groups induces a charge redistribution in the micropores of MOFs. We have shown that higher electron densities of sp²-carbon atoms in benzimidazolate ligands reduces the energy barrier to generate *COOH, which is simultaneously controlled by the mass transfer of CO₂. Our research offers an effective method of disrupting local electron neutrality in the pores of electrocatalysts/supports to activate CO₂ under electrochemical conditions.