Single atom of transition metals (iron, cobalt, etc.) anchored on N-doped carbon materials (M-N-C) have become promising alternatives to Pt/C catalyst for oxygen reduction reaction (ORR) and proton exchange membrane fuel cells (PEMFC). Dual-atom catalysts (DACs) can further improve their performance due to the synergistic effect between two adjacent metal atoms, but the structure-activity relationship of the dual-metal-atom active site remains unclear, especially the impact of coordinated nitrogen species. Herein, we use a pre-carbonization and impregnation method to construct two different nitrogen coordinated Fe-Co dual-metal-atom active sites on carbon support. The existence of bimetallic dimer structure has been proved by HAADF-STEM and XAFS characterization. XPS results suggest that the pyridinic N and pyrrolic N content is different in two Fe-Co dual-atom catalysts. The experimental and theoretical ORR activity both suggest Fe-Co active site coordinated by pyridinic nitrogen is more favorable for ORR and PEMFC performance. Our work provides a deep insight into the relationship between the N species and activity of Fe-Co dual-metal-atom ORR catalysts.
Wang et al. (Thu,) studied this question.