Improving CO2 electroreduction over ZIF-derived carbon doped with Fe-N sites by an additional ammonia treatment
Chengcheng Yan, Yifan Ye, Long Lin, Haihua Wu, Qike Jiang, Guoxiong Wang, Xinhe Bao
Index: 10.1016/j.cattod.2018.03.062
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Abstract
Iron-nitrogen-carbon (Fe-N-C) composite materials show considerable Faradaic efficiency for CO production in electrochemical CO2 reduction reaction (CO2RR), 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 CO2RR. 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.