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

The different morphologies of iron carbide encapsulated nitrogen-doped carbon nanotube and nanosheet (Fe3C@N-CNTs, Fe3C@N-CNSs) electrocatalysts were synthesized by a one-step calcination method. They were used as electrocatalysts for the oxygen reduction reaction. The electrochemical measurement results indicated that the half-wave potentials (E-1/2) on the Fe3C@N-CNTs- and Fe3C@N-CNSs-modified glassy carbon electrodes reached 0.845 V and 0.860 V, respectively. Compared with 20 wt% commercial Pt/C (0.856 V), the E-1/2 on the Fe3C@N-CNSs/GCE shifted positively. The onset potentials (E-onset) on the Fe3C@N-CNSs was 1.056 V, which was higher than that on commercial Pt/C (0.998 V) and Fe3C@N-CNTs (0.996 V). The Fe3C@N-CNSs showed a better electrocatalytic property toward ORR than Fe3C@N-CNTs, which results from the Fe3C@N-CNSs (735.58 m(2) g(-1)) with a larger specific surface area than that of Fe3C@N-CNTs (191.20 m(2) g(-1)). The stability of the Fe3C@N-CNTs was better than that of the Fe3C@N-CNSs contribution to the Fe3C particles encapsulated by the carbon nanotubes.