Electrochemical CO2 Reduction in a Continuous Non-Aqueous Flow Cell with [Ni(cyclam)]2.

A significant number of molecular catalysts have been developed for electrochemical CO2 reduction with high efficiency and selectivity; however, testing of these electrocatalysts in an application-ready system is lacking. Here, we present an example of a nonaqueous flow cell electrolyzer with [Ni(cyclam)]2+ as the homogeneous electrocatalyst for CO2 reduction. Using ferrocene as a sacrificial electron donor and ammonium salts as both electrolyte and proton donor, efficient catalytic CO2 reduction is achieved. The nonaqueous design shows high selectivity for the reduction of CO2 to CO (>80%) and achieves high current densities with a graphite felt working electrode (up to 50 mA·cm-2 with 0.5 M proton donor in MeCN solution), producing >40 mL·h-1 of CO. The choice of a molecular electrocatalyst, solvent, and proton donor are the key factors for achieving high activity with an efficient flow electrolyzer and the eventual development of a viable continuous process.