In situ self-assembly of Fe-N-C oxygen reduction catalysts and morphology evolution triggered by sulfates

Transition-metal-nitrogen-carbon catalysts have been considered one of the most promising oxygen reduction catalysts. Generally, direct pyrolysis and template approaches are popular in preparation of ORR catalysts. Yet these methods are restricted to a certain extent due to their inherent flaws. Therefore, the elaborate design and controllable synthesis of catalysts still remain challenges. Here, Polydopamine-derived Fe-N-C catalysts are in situ fabricated by self-assembly strategy. Nanorod-like catalysts were obtained by pyrolysis of FeSO 4 -Phen/PDA/F127@trimethylbenzene composite micelles. The introduction of SO 4 2- ion plays a critical role in the morphology evolution from nanospheres to nanorods with the assistance of phenanthroline. The presence of trimethylbenzene (TMB) facilitates the dispersion of single atom Fe on the surface of composite micelles. Thus the simultaneous modulation of active sites and carbon architectures on Fe-N-C catalysts were achieved by finely regulating the interfaces of composite micelles. The novel catalyst exhibits good ORR activity and durability over Pt/C catalyst with more positive half-wave potential and higher current density. The good electrocatalytic performances are attributed to the larger surface areas, hierarchical porous structures and highly active FeN 4 sites. Moreover, Zn-air battery fabricated with Fe-N-C catalysts as the air cathode display higher power density of 116 mW cm −2 and specific capacity of 713 mA h g −1 . This work will open up a new avenue for in situ fabrication of M-N-C catalysts (M=Cu, Co, Ni, Mn, Zn) via self-assembly strategy. Schematic illustration of synthetic procedure of Fe-N-C catalyst by self-assembly strategy.