Electroreduction of Carbon Dioxide Driven by the Intrinsic Defects in the Carbon Plane of a Single Fe-N4 Site

Manipulating the in-plane defects of metal-nitrogen-carbon catalysts to regulate the electroreduction reaction of CO2 (CO2RR) remains a challenging task. Here, it is demonstrated that the activity of the intrinsic carbon defects can be dramatically improved through coupling with single-atom Fe-N-4 sites. The resulting catalyst delivers a maximum CO Faradaic efficiency of 90% and a CO partial current density of 33 mA cm(-2) in 0.1 m KHCO3. The remarkable enhancements are maintained in concentrated electrolyte, endowing a rechargeable Zn-CO2 battery with a high CO selectivity of 86.5% at 5 mA cm(-2). Further analysis suggests that the intrinsic defect is the active sites for CO2RR, instead of the Fe-N-4 center. Density functional theory calculations reveal that the Fe-N-4 coupled intrinsic defect exhibits a reduced energy barrier for CO2RR and suppresses the hydrogen evolution activity. The high intrinsic activity, coupled with fast electron-transfer capability and abundant exposed active sites, induces excellent electrocatalytic performance.

Automated summary

By coupling with single-atom Fe-N-4 sites, the activity of intrinsic carbon defects can be significantly improved, leading to remarkable enhancements in electrocatalytic performance for CO2 reduction. The resulting catalyst shows high CO Faradaic efficiency, CO selectivity, and current density, demonstrating great potential for the development of rechargeable Zn-CO2 batteries.