N-doped carbon nanoflower-supported Fe-N4 motifs for high-efficiency reduction of oxygen in both alkaline and acid

Abstract Simultaneously improving the loading and accessibility of atomically dispersed metal sites to achieve high-activity and high-throughput electrocatalysis is important yet challenging. Herein, a simple method based on formamide chemistry was developed for the efficient synthesis of 3D flower-like N-doped carbons decorated with highly loaded atomic Fe-N4 motifs. Approximately twice as much atomic Fe (6.84 wt%) was loaded due to the introduction of 2,1,3-benzothiadiazole (Bz) as additional ligands in the preparation of formamide-derived binary ZnFe-NC (f-ZnFe-NC). Meanwhile, with the promotion of Bz, the f-ZnFe-NC precursor also showed improved 3D flower structure that could be robustly inherited into the formation of flower-like Fe-NC product after high-temperature treatment, leading to the obtainment of rich open pores for exposing more atomic Fe sites (site density of 26.6 umol g−1 and turnover of frequency of 1.73 s−1) for oxygen reduction electrocatalysis. Electrochemical measurements showed that the Bz-promoted synthesized Fe-NC (referred to as Bz-Fe1-NC) possessed superior onset potential (1.04 V) and half-wave potential (0.94 V), and its assembled Al-air battery provided a very large specific power of 238.2 mW cm−2 along with high-rate capability and good long-term stability.