Bio-inspired bimetallic models for electrochemical CO₂ reduction

Inspired by the carbon monoxide dehydrogenase (CODH) active site where two metal ions synergistically catalyze the interconversion between CO₂ and CO, we have developed a family of rhenium dipyridine derivatives (1-3), in which potassium 1-aza-18-crown-6-ether (KN18C6) moiety functions as a Lewis acid to assist the CO₂ reduction reaction (CORR). We found that such design leads to dramatically strong deposition on the electrode under CO₂ in the presence of potassium cation, and a clear trend for the deposition rate was observed following the flexibility of linkage between the framework and the KN18C6 moiety; the more flexible, the faster. The origin of deposition was further characterized by a series of control experiments and infrared spectroelectrochemistry (IR-SEC). Unfortunately, the deposition suppresses the subsequent C-O bond cleavage reaction.