Boosting oxygen reduction reaction with Fe and Se dual-atom sites supported by nitrogen-doped porous carbon

Dual-atomic-site catalysts (DASCs), as an extension of single-atom catalysts (SACs), have attracted increasing attention owing to the synergistic effect. However, the study of DASCs is still at the early stages and mainly based on metal atom pairs. More experimental and theoretical exploration needed for further guiding the reasonable design of diatomic active sites. Herein, remarkable activity for oxygen reduction reaction (ORR) of Se1-NC single-atom catalyst was discovered, and then Fe/Se dual-atom catalysts were constructed to demonstrate the dual-atom sites synergistic effect. Encouraging, the Fe1Se1-NC catalyst displays significant enhancement for ORR towards Fe1-NC and Se1-NC in both alkaline and acid electrolytes. Spectroscopic characterizations and theoretical calculations reveal that there are multiple effects for the introduction of Se, especially for supplying new active sites, and effectively tuning charge redistribution and the spin-state of Fe active sites, which presenting a new strategy to improve the electrochemical performance based on the metal-nonmetal dual-atomic-site catalysts.