Honeycomb-like 3D N-, P-codoped porous carbon anchored with ultrasmall Fe2P nanocrystals for efficient Zn-air battery

Fabrication of transition metal phosphides/carbon hybrids as electrocatalysts for oxygen reduction reaction (ORR) has great significance for developing clean energy conversion and storage devices based on earth abundant elements. In this work, we prepared 3D N,P-codoped porous carbon supported with ultrasmall Fe 2 P nanoparticles (Fe 2 P/NPC) as high-efficient ORR catalyst by a simple grinding-calcination strategy. As the pore-forming agent, ZnO nanospheres can be in-situ eliminated and generate abundant porous structures which are beneficial to mass transfer. Meanwhile, the large BET surface area (1288 m 2  g −1 ) and pore volume (1.23 cm 3  g −1 ) of Fe 2 P/NPC can provide more contact active centres for ORR. In alkaline solution, Fe 2 P/NPC performs excellent ORR activity with the positive onset potential (0.997 V) and half-wave potential (0.872 V), which are more positive than those of the commercial Pt/C (0.977 and 0.812 V). In addition, Fe 2 P/NPC can be used as air cathode catalyst in a Zn-air battery whose open circuit voltage (1.469 V) is larger than that of the commercial Pt/C (1.332 V) based one. This work provides new strategy to prepare transition metal phosphides/carbon hybrids for electrocatalysis and clean energy conversion systems.