High electrocatalytic performance of Fe3C-encapsulated N-doped carbon nanotubes and nanosheets for oxygen reduction reaction

•The Fe3C@N-CNTs and Fe3C@N-CNSs electrocatalysts were successfully prepared.•The specific surface area of Fe3C@N-CNSs electrocatalyst reached 735.58 m2 g−1.•Carbon nanotubes surround Fe3C nanoparticles to increase the stability of Fe3C@N-CNTs.•The electrocatalytic activity of Fe3C@N-CNTs and Fe3C@N-CNSs were superior to commercial 20% Pt/C.