Engineering iron carbide catalyst with aerophilic and electron-rich surface for improved electrochemical CO 2 reduction

Highly efficient electrocatalyst for carbon dioxide reduction (CO RR) is desirable for converting CO into carbon-based chemicals and reducing anthropogenic carbon emission. Regulating catalyst surface to improve the affinity for CO and the capability of CO activation is the key to high-efficiency CO RR. In this work, we develop an iron carbide catalyst encapsulated in nitrogenated carbon (SeN-Fe C) with an aerophilic and electron-rich surface by inducing preferential formation of pyridinic-N species and engineering more negatively charged Fe sites. The SeN-Fe C exhibits an excellent CO selectivity with a CO Faradaic efficiency (FE) of 92 % at -0.5 V (vs. RHE) and remarkably enhanced CO partial current density as compared to the N-Fe C catalyst. Our results demonstrate that Se doping reduces the Fe C particle size and improves the dispersion of Fe C on nitrogenated carbon. More importantly, the preferential formation of pyridinic-N species induced by Se doping endows the SeN-Fe C with an aerophilic surface and improves the affinity of the SeN-Fe C for CO . Density functional theory (DFT) calculations reveal that the electron-rich surface, which is caused by pyridinic N species and much more negatively charged Fe sites, leads to a high degree of polarization and activation of CO molecule, thus conferring a remarkably improved CO RR activity on the SeN-Fe C catalyst.