Improving CO2 electroreduction over ZIF-derived carbon doped with Fe-N sites by an additional ammonia treatment

Abstract Iron-nitrogen-carbon (Fe-N-C) composite materials show considerable Faradaic efficiency for CO production in electrochemical CO 2 reduction reaction (CO 2 RR), which are promising alternatives to noble metal catalysts. However, reported results exhibit limited CO current densities. Herein, an additional ammonia treatment process is explored to futher improve the activity of a ZIF-derived carbon material doped with Fe-N sites. Physicochemical characterizations reveal that ammonia treatment facilitates the sublimation of residual Zn species and etching of unstable carbon mioeties, thus increasing the loading of Fe-N active sites and specific surface area. The increased specific surface area effectively maximizes the exposure of Fe-N active sites and facilitates mass transfer during the CO 2 RR. With an additional pyrolysis in ammonia, the optimal catalyst shows higher CO Faradaic efficiency and much improved CO current density, outperforming other reported Fe-N-C catalysts.