A Nitrogen-Doped Carbon Catalyst for Electrochemical CO₂ Conversion to CO with High Selectivity and Current Density

We report characterization of a non-precious metal-free catalyst for the electrochemical reduction of CO₂ to CO; namely, a pyrolyzed carbon nitride and multiwall carbon nanotube composite. This catalyst exhibits a high selectivity for production of CO over H₂ (approximately 98 % CO and 2 % H₂ ), as well as high activity in an electrochemical flow cell. The CO partial current density at intermediate cathode potentials (V=-1.46 V vs. Ag/AgCl) is up to 3.5× higher than state-of-the-art Ag nanoparticle-based catalysts, and the maximum current density is 90 mA cm^-2 . The mass activity and energy efficiency (up to 48 %) were also higher than the Ag nanoparticle reference. Moving away from precious metal catalysts without sacrificing activity or selectivity may significantly enhance the prospects of electrochemical CO₂ reduction as an approach to reduce atmospheric CO₂ emissions or as a method for load-leveling in relation to the use of intermittent renewable energy sources.