Facile fabrication of N-doped hierarchical porous carbon@CNT coaxial nanocables with high performance for energy storage and conversion

Developing a facile and cost-effective design and fabrication method to realize an optimal carbon nanoarchitecture containing hierarchical pores, appropriate N doping and high conductivity for high-performance in energy storage and conversion is still a challenge. Herein, we have facilely achieved an intriguing heterostructure of N-doped hierarchical porous carbon@CNT coaxial nanocables (HPNCNTs) via a one-step carbonization of resorcinol–melamine–formaldehyde resin (RMF)@CNT shell@core nanostructures. Significantly, we have demonstrated that the RMF@CNT shell@core nanostructures, with their inherent microporous structure and proper N-containing functionalities, represent the ideal precursor for realizing carbon heterostructures for electrochemical performance optimization for supercapacitors and in the oxygen reduction reaction (ORR). The results show that the HPNCNTs exhibit a specific capacitance of 284 F g−1, much higher than that of CNTs and most of the reported N-doped carbons, a good rate capability and a robust cycling performance with no capacity fading even after 6000 cycles. Furthermore, HPNCNTs show high electrocatalytic activity for the ORR with an onset potential of −0.04 V (vs. Ag/AgCl), a dominant four-electron pathway (n = 3.84), long-term stability, and excellent resistance to crossover effects superior to that of the commercial Pt/C. The present investigation opens the avenue for creating carbon heterostructures with a desirable porous tissue and morphology through a facile and general route for future high-performance renewable energy storage and conversion devices.