Dual MOF-derived Fe/N/P-tridoped carbon nanotube as high-performance oxygen reduction catalysts for zinc-air batteries

The controllable construction of Fe,N co-doped carbon (Fe-N-C) nanocomposite has highly potential in replacing the noble metal catalysts. Herein, the Fe/N/P-tridoped expanded carbon nanotubes (P-Fe-N-CNTs) are prepared according to a simple one-step pyrolysis procedure. The unexpanded Fe-N-C carbon nanotubes (Feu-N-CNTs) are also fabricated for comparision. The expanded P-Fe-N-CNTs yields a high half-wave potential (E1/2) of 0.8843 V compared with unexpanded Feu-N-CNT and commercial Pt/C. Furthermore, the expanded P-Fe-N-CNT as catalyst of Zn-air battery achieves high electrocatalytic performance, which is better than commercial Pt/C material. The unique architecture of expanded P-Fe-N-CNTs can improve the specific surface area and promote the formation the abundant active site, thus promoting the ORR kinetic process. Density functional theory (DFT) calculations futher confirm that suitable P doping can regulate the electronic structures of the active catalytic sites. The work provides a controllable way to prepare rational expanded P-Fe-N-CNTs for different applications, especially in Zn-air battery.