The built-in electric field across FeN/Fe 3 N interface for efficient electrochemical reduction of CO 2 to CO.

Nanostructured metal-nitrides have attracted tremendous interest as a new generation of catalysts for electroreduction of CO 2 , but these structures have limited activity and stability in the reduction condition. Herein, we report a method of fabricating FeN/Fe 3 N nanoparticles with FeN/Fe 3 N interface exposed on the NP surface for efficient electrochemical CO 2 reduction reaction (CO 2 RR). The FeN/Fe 3 N interface is populated with Fe-N 4 and Fe-N 2 coordination sites respectively that show the desired catalysis synergy to enhance the reduction of CO 2 to CO. The CO Faraday efficiency reaches 98% at -0.4 V vs. reversible hydrogen electrode, and the FE stays stable from -0.4 to -0.9 V during the 100 h electrolysis time period. This FeN/Fe 3 N synergy arises from electron transfer from Fe 3 N to FeN and the preferred CO 2 adsorption and reduction to *COOH on FeN. Our study demonstrates a reliable interface control strategy to improve catalytic efficiency of the Fe-N structure for CO 2 RR.