ZIF-8-assisted pyrolysis to synthesize cobalt-modified nitrogen‑sulfur co-doped carbon nanofibers for zinc-air batteries

Oxygen reduction reaction (ORR) electrocatalysts have the advantages of high activity, high durability and inexpensive, which are promising for promoting the mass commercialization of renewable fuel cells and metal-air batteries. Uniform N and S co-doping can enhance the integral activity and conductivity of catalysts has been shown to be important in ORR electrocatalysis. In this study, cobalt-modified N, S co-doped carbon nanofibers (Co-NSC-R) were successfully synthesized by using ZIF-8 as a template-assisted pyrolysis. The N, S co-doped carbon matrix firmly anchored the Co-Nx sites on the entangled carbon fibers, which efficiently regulated the electronic structure of the Co-Nx-C sites and greatly ensured their oxygen electrocatalytic activity. In addition, the half-wave potential of the Co-NSC-R catalyst reaches 0.861 V and has superior resistance to methanol intoxication and cycling stability. The assembled zinc-air batteries (ZABs) have a maximum power density of 73.1 mW cm−2, a high specific capacity of 752.7 mAh g−1 and a long-term durability of 94 h. This work provides ideas for the application of metal-modified heteroatom-doped porous carbon nanofibers as excellent ORR catalysts.