Fourteen-membered macrocyclic cobalt complex for the electrolysis of low-concentration gaseous carbon dioxide with high faradaic efficiency toward carbon monoxide†
Abstract
It is necessary to lower the overpotential for CO2 reduction to enable the practical application of CO2 electrolysis in industrial scenarios. In gaseous CO2 electrolysis with a gas diffusion electrode, a fourteen-membered macrocyclic cobalt complex (Co 14-membered ring: Co–14MR) was found to be an excellent cathode catalyst for the reduction of CO2 to CO. A high current density (101 mA cm−2 at −2.05 V (Ag/AgCl)), high faradaic efficiency (>99%), low overpotential (onset potential of CO formation: −0.13 V (RHE)), and high durability (stable performance until turn over number (TON) = 2.3 × 104 per Co atom) were achieved. Moreover, CO was generated with a faradaic efficiency of 95% during CO2 electrolysis with the Co–14MR cathode under a low CO2 concentration (10% CO2). The single-atom Co site in the Co–14MR catalyst enabled the near-complete suppression of undesired H2 evolution.