The controlled synthesis of Fe3C/Co/N-doped hierarchically structured carbon nanotubes for enhanced electrocatalysis.

SYNOPSIS TOC Hierarchical structured Fe 3 C/Co/N-doped carbon nanotubes were rationally designed and controllable synthesized by a novel and efficient multi-step approach. Benefiting from the unique structural and composition characteristics, the catalysts exhibited excellent electrochemical performance for oxygen reduction reaction in alkaline electrolyte, even better than commercial Pt/C. This introduced synthesis approach can open up new opportunities for the design and synthesis of other MOF assemblies and their derivatives with high performance, not only in the energy field, but also in other frontiers. • Hierarchically porous Fe 3 C/Co/N-doped carbon nanotubes are designed and prepared. • The components effects on the electro activity have been systematically studied. • It is a general way for the preparation of other catalysts with high performances. It is critical and challenging for preparing nonprecious metal catalysts with high catalytic performance in fuel cells and metal-air batteries. In this work, we developed an efficient multistep approach to synthesize metal-organic framework (MOF)@Fe-Phen nanotube-derived composite electrocatalyst (CNCo-n@Fe-x), which consisted of N-riched mesoporous carbon nanotubes with high graphitization degree and uniformly distributed active sites (Co, Fe 3 C, N-C, Fe-Nx, and Co-Nx). Experimental results indicated that the bimetallic doping was superior to a single metal. Benefiting from the unique hierarchical structure and the synergies among the active sites also the high conductivity, as expected, the composite nanotubes exhibited excellent electrochemical performance for oxygen reduction reaction in alkalinity electrolyte, even better than the commercial Pt/C catalyst. More importantly, when used for constructing the air electrode of the Zn-air battery, CNCo-5@Fe-2 nanotubes also displayed high performance. [ABSTRACT FROM AUTHOR]