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

Nanostructured metal-nitrides have attracted tremendous interest as a new generation of catalysts for electroreduction of CO, but these structures have limited activity and stability in the reduction condition. Herein, we report a method of fabricating FeN/FeN nanoparticles with FeN/FeN interface exposed on the NP surface for efficient electrochemical CO reduction reaction (CORR). The FeN/FeN interface is populated with Fe-N and Fe-N coordination sites respectively that show the desired catalysis synergy to enhance the reduction of CO 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/FeN synergy arises from electron transfer from FeN to FeN and the preferred CO 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 CORR.