N-, Fe-Doped carbon sphere/oriented carbon nanofiber nanocomposite with synergistically enhanced electrochemical activities

Catalysts for the oxygen reduction reaction (ORR) are crucial in metal-air batteries, fuel cells and other electrochemical devices. Developing heteroatom-doped carbon catalysts with high performance and stability in alkaline media for practical application of metal-air batteries or in acidic media for practical application of proton exchange membrane fuel cells is still difficult and challenging. Here, we report the N-, Fe-doped carbon sphere/oriented carbon nanofiber nanocomposite (NFe-CS/CNF). N-, Fe-doped carbon spheres (NFe-CS) were derived from p-phenylenediamine and oriented N-, Fe-doped carbon nanofibers (NFe-CNF) were derived from o-phenylenediamine. 3.89 at% of N and 0.38 at% of Fe were doped in a typical product, which has high surface area. The typical product exhibits a high ORR activity and stability in acidic media and reveals superior stability and tolerance to methanol than Pt/C. In alkaline media, the typical product shows superior activity to Pt/C. The performance of a zinc-air full cell under real battery operation conditions indicates that the typical product is a competitive alternative to commercial PtC. The unique structure of NFe-CS/CNF could create strong interactions between the nanospheres and oriented nanofibers, promote charger transfer at the interface and improve the conductivity. This work provides a new fundamental understanding and design strategy for excellent carbon-based ORR catalysts.