Multicomponent Doped Sugar-Coated Haws Stick-like Nanofibers as Efficient Oxygen Reduction Reaction Catalysts for the Zn–Air Battery

In this work, unique sugar-coated haws stick-like core–shell ZIF-67@PAN-HCCP-MIM-FeCl3 nanofibers were successfully prepared by electrospinning and an in situ nanocrystal growth process. After carbonization of the as-synthesized nanofibers at various temperatures, the resulting sample Fe/Co-N/P-9 (carbonized at 900 °C) retained the presented a sugar-coated haws stick-like structure. The internal carbon nanofiber acts like a “stick” as a support, the “haws” composed of Co2P and Fe5C2 nanoparticles act as catalytic active sites, and the graphite carbon acts as “sugar” to protect particles from detachment. The channel gap between inner core and outer layer can improve the mass transfer process. Owing to these special structure and unique composition features, Fe/Co-N/P-9 exhibited excellent oxygen reduction reaction (ORR) performance with an onset potential of 0.96 V (vs RHE) and a half wave potential of 0.85 V (vs RHE) in 0.1 M KOH solution. Fe/Co-N/P-9 also showed good catalytic stability and methanol tolerance. In addition, the rechargeable Zn–air battery fabricated by Fe/Co-N/P-9 exhibited a galvanostatic discharge voltage of 1.25 V, a higher specific capacity of 565 mAh/gZn, and a better cycle stability than Pt/C+RuO2.