Highly active oxygen evolution integrated with efficient CO ₂ to CO electroreduction

Significance Electrochemical reduction of CO 2 to useful chemicals or fuels is critical to closing the carbon cycle and preventing further deterioration of the environment/climate. This work addresses the low-energy-efficiency problem of CO 2 reduction limited by sluggish oxygen evolution reaction (OER) on the anode side. The only active OER catalysts for coupling CO 2 reduction in neutral conditions are based on noble metals such as Ir, Ru, and gold. Herein, we developed a nonprecious-metal-based OER anode with higher activity and stability than those based on noble-metal catalysts IrO 2 and Ir/C. We integrated our anode with a selective CO 2 reduction cathode to achieve >97% conversion of CO 2 to CO and a record-setting high energy efficiency for CO 2 conversion.