Metal Oxide/Nitrogen-Doped Carbon Catalysts Enables Highly E ffi cient CO2 Electroreduction

The metal oxide/nitrogen-doped carbon(NC) compounds zirconium oxide/NC(Zr O/NC) and cerium oxide/NC(Ce O/NC) were synthesized via the pyrolysis of polyaniline on the metal oxide surface. The characterization of the Zr O/NC and Ce O/NC catalysts showed more active COreduction reaction activity than that of NC catalyst without metal oxide. Gas chromatography analysis revealed that CO and Hwere the primary products, and no liquid-phase products were detected via proton nuclear magnetic resonance spectroscopy or high-performance liquid chromatography. The maximum Faraday effi ciency of Zr O/NC reached 90% at-0.73 V(vs. RHE), with the current density of CO at 5.5 m A/cm~2; this Faraday effi ciency value was higher than that of NC(41%), with the current density of CO at 3.1 m A/cm~2. The interaction between the metal oxide and carbon allowed the effi cient formation of defect sites, especially imine-type nitrogen, strengthening the adsorption of the key reaction intermediate COand thus promoting the COreduction reaction.