Fe and N Co-Doped Porous Carbon Nanospheres with High Density of Active Sites for Efficient CO2 Electroreduction

To enhance the electrocatalytic performance of transition metal and nitrogen codoped carbon (M-N-C) for the CO2 electroreduction reaction, we present a Fe and N codoped porous carbon nanosphere (Fe-N-PC) with a high density of single-atom iron active sites and a few Fe clusters, as indicated by high-resolution TEM and EXAFS, using SiO2 as the protecting shell to restrict isolated Fe atoms and to trap the volatile N-containing species. The Fe doping content can reach as high as 3.9 wt %. The Fe-N-PC catalyst exhibits an excellent performance for converting CO2 to CO with high Faradaic efficiency (similar to 90%) and remarkable partial CO current density (11.44 mA cm(-2)) at -0.49 V. Probing analysis and selective chemical modification reveal that both Fe atom and ortho-C of N atoms play a synergetic role in enhancing CO2RR activity. DFT calculations reveal that the presence of amorphous Fe clusters can facilitate the desorption of CO from the surface of the catalyst, thus further improving the CO2RR activity. This work presents a general strategy to synthesize advanced M-N-C material with high density of single atom active sites, which could be used as an efficient electrocatalyst for CO2RR, ORR et al.