Turning manganese into gold: Efficient electrochemical CO2 reduction by a fac-Mn(apbpy)(CO)3Br complex in a gas–liquid interface flow cell

The electrochemical reduction of carbon dioxide (CO2RR) is a viable route for the transformation of intermittent renewable energy into high energy density chemical vectors (e.g. CO) or into fuels. Differently from metal nanoparticle electrocatalysts, the use of organometallic molecular complexes affords more efficient metal utilization, limits poisoning phenomena and allows the tuning of selectivity by varying the electronic and coordination properties of the metal center. Herein the organometallic complex (fac-Mn(apbpy)(CO)3Br) (apbpy = 4-(4-aminophenyl)-2,2′-bipyridine) was covalently anchored on a gas diffusion layer which was further employed as cathode in an aqueous gas–liquid interface complete electrolysis flow cell microreactor. The decorated gas diffusion layer electrode was able to convert CO2 into CO and HCOOH with faradaic efficiencies (FE) of 76% and 10% with a CO-productivity close to 70 Nl min−1 gMn−1 reaching CO2RR turnover numbers up to 1.6·105. This result largely outperforms a state-of-the-art gold nanoparticle electrocatalyst (Au/C 10 wt%) operating in the same cell conditions.