Efficient ultra-low voltage electrolysis of CO2 coupling with hydrazine oxidation degradation

Abstract

Transforming carbon dioxide (CO2) into valuable fuels or chemicals through electrolysis represents a promising approach to reduce the carbon footprint. Conventional CO2 electrolysis yet faces a challenge in low energy efficiency due to the energy-intensive oxygen evolution reaction (OER) occurring at the anode. In this study, we present an advanced CO2 electrolysis system that pairs cathodic CO2 reduction with anodic degradation of hydrazine oxidation reaction (HzOR), enabling efficient CO2 electrolysis at an ultra-low voltage. To achieve this objective, two precious-metal-free electrocatalysts have been designed and fabricated. Specifically, a nickel single-atom catalyst anchored on porous carbon nanofibers has been developed for cathodic CO2-to-CO conversion, while a flower-like Ni2Fe2N catalyst grown in-situ on nickel foam has been developed for anodic HzOR. We demonstrate high efficiency of CO production (FECO > 80%) at 100 mA cm−2 with an applied voltage of only 0.45 V by simultaneously degrading hydrazine in a flow cell.